ReasonBlocks

ReasonBlocks is a Y Combinator (Spring 2026) startup building a drop-in runtime layer that makes production AI agents observable, self-correcting, and cheaper to run. The platform detects failing agent trajectories (loops and redundant work), compresses stale tool outputs and message histories to cut token spend, and builds a private learning library of reasoning patterns (E-traces) that steer future runs. It ships as a Python SDK with first-party integrations for LangChain, LangGraph, the OpenAI Agents SDK, and the Anthropic Claude / Claude Agent SDK, plus a language-agnostic REST API (rb-api) so any custom agent harness can wire in over three HTTP calls. Reported results include a 42% accuracy gain and ~52% token reduction on SWE-bench Pro.

ReasonBlocks publishes 9 APIs on the APIs.io network, including Billing API, Codebase Findings API, Health API, and 6 more. Tagged areas include Company, AI Agents, Agent Observability, LLM, and Developer Tools.

ReasonBlocks’ developer surface includes documentation, API reference, getting-started guide, authentication, sandbox, and 17 more developer resources.

🌐 Visit website 📡 Source on GitHub
37.2/100 thin ▬ flat Agent 34/100 agent ready Full breakdown ↓
scored 2026-08-20 · rubric v0.12.0
AccessSelf serve
9 APIs 1 MCP Servers
CompanyAI AgentsAgent ObservabilityLLMDeveloper ToolsToken OptimizationAgent SteeringMachine-LearningArtificial IntelligenceSDK

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-08-20 · rubric v0.12.0
Composite quality — 37.2/100 · thin
Contract Quality 12.5 / 25
Developer Ergonomics 13.2 / 20
Access Clarity 0.0 / 20
Operational Transparency 1.4 / 13
Contract Governance 2.0 / 12
Discoverability 8.2 / 10
Agent readiness — 34/100 · agent ready
Machine-Readable Contract 18 / 18
Agentic Access Contract 10 / 10
Documented Reversibility 0 / 6
MCP Server 0 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 8 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 0 / 7
Typed Event Surface 0 / 6
Agent Skills 5 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
A2A Agent Card 0 / 8
Dry-Run / Simulate Mode 0 / 4
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/reasonblocks: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 9

Individual APIs this provider publishes, each with its own machine-readable definition.

ReasonBlocks Billing API

The Billing API from ReasonBlocks — 1 operation(s) for billing.

ReasonBlocks Codebase Findings API

The Codebase Findings API from ReasonBlocks — 5 operation(s) for codebase findings.

ReasonBlocks Health API

The Health API from ReasonBlocks — 1 operation(s) for health.

ReasonBlocks monitor API

The monitor API from ReasonBlocks — 11 operation(s) for monitor.

ReasonBlocks Monitor Telemetry API

The Monitor Telemetry API from ReasonBlocks — 11 operation(s) for monitor telemetry.

ReasonBlocks Monitors API

The Monitors API from ReasonBlocks — 1 operation(s) for monitors.

ReasonBlocks Pattern Library API

The Pattern Library API from ReasonBlocks — 2 operation(s) for pattern library.

ReasonBlocks Patterns & Traces API

The Patterns & Traces API from ReasonBlocks — 2 operation(s) for patterns & traces.

ReasonBlocks Scoring API

The Scoring API from ReasonBlocks — 1 operation(s) for scoring.

Scroll for all 9

Open Collections 10

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

ReasonBlocks Billing API

OPEN COLLECTION

ReasonBlocks Billing Codebase Findings API

OPEN COLLECTION

ReasonBlocks Billing Health API

OPEN COLLECTION

ReasonBlocks Billing monitor API

OPEN COLLECTION

ReasonBlocks Billing Monitor Telemetry API

OPEN COLLECTION

ReasonBlocks Billing Monitors API

OPEN COLLECTION

ReasonBlocks Billing Pattern Library API

OPEN COLLECTION

ReasonBlocks Billing Patterns & Traces API

OPEN COLLECTION

ReasonBlocks Billing Scoring API

OPEN COLLECTION

Scroll for all 10

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

ReasonBlocks MCP Server

MCP SERVER

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Reasonblocks Authentication

http · 1 scheme

SECURITY

Reasonblocks Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Reasonblocks Agentic Access

32 operations · 18 acting

32 operations · 18 acting

AGENTIC

Resources

Get Started 3

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 GettingStarted
GettingStarted
 Sandbox
Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation
Documentation
 APIReference
APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt
LLMsTxt
 MCPServer
MCPServer
 AgenticAccess
AgenticAccess
 AgentSkill
AgentSkill

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Conformance
Conformance
 ErrorCatalog
ErrorCatalog
 Lifecycle
Lifecycle
 Conventions
Conventions
 DataModel
DataModel

Build 3

SDKs, sample code, and the tooling you integrate with

GitHubOrganization
GitHubOrganization
 Packages
Packages
 SDKs
SDKs

Access & Security 2

Authentication, authorization, and security posture

Authentication
Authentication
 DomainSecurity
DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Deprecation
Deprecation

Company 1

The organization behind the API

Website
Website

Other 1

Properties that don't map to a standard resource type

Overlay
Overlay

Source (apis.yml)

apis.yml Raw ↑ 
aid: reasonblocks
name: ReasonBlocks
description: ReasonBlocks is a Y Combinator (Spring 2026) startup building a drop-in runtime layer that makes production AI
  agents observable, self-correcting, and cheaper to run. The platform detects failing agent trajectories (loops and redundant
  work), compresses stale tool outputs and message histories to cut token spend, and builds a private learning library of
  reasoning patterns (E-traces) that steer future runs. It ships as a Python SDK with first-party integrations for LangChain,
  LangGraph, the OpenAI Agents SDK, and the Anthropic Claude / Claude Agent SDK, plus a language-agnostic REST API (rb-api)
  so any custom agent harness can wire in over three HTTP calls. Reported results include a 42% accuracy gain and ~52% token
  reduction on SWE-bench Pro.
url: https://raw.githubusercontent.com/api-evangelist/reasonblocks/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- y-combinator
x-tier: profiled
x-tier-reason: portfolio-lead-enriched
accessModel:
  pricing: unknown
  onboarding: self-serve
  trial: false
  try_now: false
  public: false
  label: Self-serve signup
  confidence: medium
  source:
  - authentication
  generated: '2026-07-22'
  method: derived
image: https://reasonblocks.com/rb.png
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-21'
tags:
- Company
- AI Agents
- Agent Observability
- LLM
- Developer Tools
- Token Optimization
- Agent Steering
- Machine-Learning
- Artificial Intelligence
- SDK
tags_raw:
- Company
- AI Agents
- Agent Observability
- LLM
- Developer Tools
- Token Optimization
- Agent Steering
- Machine Learning
- Artificial Intelligence
- SDK
apis:
- aid: reasonblocks:reasonblocks-billing-api
  name: ReasonBlocks Billing API
  description: The Billing API from ReasonBlocks — 1 operation(s) for billing.
  humanURL: https://docs.reasonblocks.com/api-reference/rest-api/overview
  baseURL: https://rb-api.reasonblocks.com
  tags:
  - Billing
  properties:
  - type: OpenAPI
    url: openapi/reasonblocks-billing-api-openapi.yml
  - type: Documentation
    url: https://docs.reasonblocks.com/introduction
  - type: APIReference
    url: https://rb-api.reasonblocks.com/docs
  - type: GettingStarted
    url: https://docs.reasonblocks.com/quickstart
- aid: reasonblocks:reasonblocks-codebase-findings-api
  name: ReasonBlocks Codebase Findings API
  description: The Codebase Findings API from ReasonBlocks — 5 operation(s) for codebase findings.
  humanURL: https://docs.reasonblocks.com/api-reference/rest-api/overview
  baseURL: https://rb-api.reasonblocks.com
  tags:
  - Codebase Findings
  properties:
  - type: OpenAPI
    url: openapi/reasonblocks-codebase-findings-api-openapi.yml
  - type: Documentation
    url: https://docs.reasonblocks.com/introduction
  - type: APIReference
    url: https://rb-api.reasonblocks.com/docs
  - type: GettingStarted
    url: https://docs.reasonblocks.com/quickstart
- aid: reasonblocks:reasonblocks-health-api
  name: ReasonBlocks Health API
  description: The Health API from ReasonBlocks — 1 operation(s) for health.
  humanURL: https://docs.reasonblocks.com/api-reference/rest-api/overview
  baseURL: https://rb-api.reasonblocks.com
  tags:
  - Health
  properties:
  - type: OpenAPI
    url: openapi/reasonblocks-health-api-openapi.yml
  - type: Documentation
    url: https://docs.reasonblocks.com/introduction
  - type: APIReference
    url: https://rb-api.reasonblocks.com/docs
  - type: GettingStarted
    url: https://docs.reasonblocks.com/quickstart
- aid: reasonblocks:reasonblocks-monitor-api
  name: ReasonBlocks monitor API
  description: The monitor API from ReasonBlocks — 11 operation(s) for monitor.
  humanURL: https://docs.reasonblocks.com/api-reference/rest-api/overview
  baseURL: https://rb-api.reasonblocks.com
  tags:
  - Monitors
  tags_raw:
  - monitor
  properties:
  - type: OpenAPI
    url: openapi/reasonblocks-monitor-api-openapi.yml
  - type: Documentation
    url: https://docs.reasonblocks.com/introduction
  - type: APIReference
    url: https://rb-api.reasonblocks.com/docs
  - type: GettingStarted
    url: https://docs.reasonblocks.com/quickstart
- aid: reasonblocks:reasonblocks-monitor-telemetry-api
  name: ReasonBlocks Monitor Telemetry API
  description: The Monitor Telemetry API from ReasonBlocks — 11 operation(s) for monitor telemetry.
  humanURL: https://docs.reasonblocks.com/api-reference/rest-api/overview
  baseURL: https://rb-api.reasonblocks.com
  tags:
  - Monitor Telemetry
  properties:
  - type: OpenAPI
    url: openapi/reasonblocks-monitor-telemetry-api-openapi.yml
  - type: Documentation
    url: https://docs.reasonblocks.com/introduction
  - type: APIReference
    url: https://rb-api.reasonblocks.com/docs
  - type: GettingStarted
    url: https://docs.reasonblocks.com/quickstart
- aid: reasonblocks:reasonblocks-monitors-api
  name: ReasonBlocks Monitors API
  description: The Monitors API from ReasonBlocks — 1 operation(s) for monitors.
  humanURL: https://docs.reasonblocks.com/api-reference/rest-api/overview
  baseURL: https://rb-api.reasonblocks.com
  tags:
  - Monitors
  properties:
  - type: OpenAPI
    url: openapi/reasonblocks-monitors-api-openapi.yml
  - type: Documentation
    url: https://docs.reasonblocks.com/introduction
  - type: APIReference
    url: https://rb-api.reasonblocks.com/docs
  - type: GettingStarted
    url: https://docs.reasonblocks.com/quickstart
- aid: reasonblocks:reasonblocks-pattern-library-api
  name: ReasonBlocks Pattern Library API
  description: The Pattern Library API from ReasonBlocks — 2 operation(s) for pattern library.
  humanURL: https://docs.reasonblocks.com/api-reference/rest-api/overview
  baseURL: https://rb-api.reasonblocks.com
  tags:
  - Pattern Library
  properties:
  - type: OpenAPI
    url: openapi/reasonblocks-pattern-library-api-openapi.yml
  - type: Documentation
    url: https://docs.reasonblocks.com/introduction
  - type: APIReference
    url: https://rb-api.reasonblocks.com/docs
  - type: GettingStarted
    url: https://docs.reasonblocks.com/quickstart
- aid: reasonblocks:reasonblocks-patterns-traces-api
  name: ReasonBlocks Patterns & Traces API
  description: The Patterns & Traces API from ReasonBlocks — 2 operation(s) for patterns & traces.
  humanURL: https://docs.reasonblocks.com/api-reference/rest-api/overview
  baseURL: https://rb-api.reasonblocks.com
  tags:
  - Patterns & Traces
  properties:
  - type: OpenAPI
    url: openapi/reasonblocks-patterns-traces-api-openapi.yml
  - type: Documentation
    url: https://docs.reasonblocks.com/introduction
  - type: APIReference
    url: https://rb-api.reasonblocks.com/docs
  - type: GettingStarted
    url: https://docs.reasonblocks.com/quickstart
- aid: reasonblocks:reasonblocks-scoring-api
  name: ReasonBlocks Scoring API
  description: The Scoring API from ReasonBlocks — 1 operation(s) for scoring.
  humanURL: https://docs.reasonblocks.com/api-reference/rest-api/overview
  baseURL: https://rb-api.reasonblocks.com
  tags:
  - Scoring
  properties:
  - type: OpenAPI
    url: openapi/reasonblocks-scoring-api-openapi.yml
  - type: Documentation
    url: https://docs.reasonblocks.com/introduction
  - type: APIReference
    url: https://rb-api.reasonblocks.com/docs
  - type: GettingStarted
    url: https://docs.reasonblocks.com/quickstart
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: DeveloperPortal
  url: https://docs.reasonblocks.com/
- type: Documentation
  url: https://docs.reasonblocks.com/introduction
- type: APIReference
  url: https://rb-api.reasonblocks.com/docs
- type: GettingStarted
  url: https://docs.reasonblocks.com/quickstart
- type: GitHubOrganization
  url: https://github.com/ReasonBlocks
- type: Website
  url: https://reasonblocks.com
- type: Authentication
  url: authentication/reasonblocks-authentication.yml
- type: Packages
  url: packages/reasonblocks-packages.yml
- type: SDKs
  url: packages/reasonblocks-packages.yml
- type: LLMsTxt
  url: llms/reasonblocks-llms.txt
- type: MCPServer
  url: mcp/reasonblocks-mcp.yml
- type: Overlay
  url: overlays/reasonblocks-openapi-overlay.yaml
- type: Conformance
  url: conformance/reasonblocks-conformance.yml
- type: ErrorCatalog
  url: errors/reasonblocks-problem-types.yml
- type: Lifecycle
  url: lifecycle/reasonblocks-lifecycle.yml
- type: Deprecation
  url: https://docs.reasonblocks.com/api-reference/rest-api/versioning
- type: Conventions
  url: conventions/reasonblocks-conventions.yml
- type: DataModel
  url: data-model/reasonblocks-data-model.yml
- type: Sandbox
  url: sandbox/reasonblocks-sandbox.yml
- type: DomainSecurity
  url: security/reasonblocks-domain-security.yml
- type: AgenticAccess
  url: agentic-access/reasonblocks-agentic-access.yml
- type: AgentSkill
  url: skills/_index.yml
x-enrichment:
  date: '2026-07-21'
  status: enriched
  artifacts_added: 18
  pass: local-v1