CompanyStack

CompanyStack (companystack.co.uk) is a UK company data provider built on Companies House records. Per its official MCP Registry entry (uk.co.companystack/mcp, v0.1.1) it offers search, officers, owners/PSCs, shareholders, filings and filed accounts/financials, newly incorporated companies and KYB checks, served as a remote streamable-HTTP MCP server at https://api.companystack.co.uk/mcp authenticated with a CompanyStack API key (X-Api-Key, cs_ prefix) or OAuth sign-in.

CompanyStack is listed with 1 API on the APIs.io network. Tagged areas include Company, Company Data, Companies House, United Kingdom, and KYB.

CompanyStack’s developer surface includes changelog, authentication, documentation, and 3 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

11.4/100 emerging Agent 6/100 agent aware Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

1 API 1 MCP Servers

Company Company Data Companies House United Kingdom KYB Business Verification MCP

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 11.4/100 · emerging

Contract Quality 0.0 / 21

Developer Ergonomics 3.6 / 17

Access Clarity 0.0 / 17

Operational Transparency 1.6 / 11

Contract Governance 0.0 / 10

Discoverability 5.6 / 9

Regulatory Posture 0.9 / 15

Agent readiness — 6/100 · agent aware

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Machine-Readable Contract +18 pts — api_specs includes an OpenAPI document Ask about this →
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author Ask about this →
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented) Ask about this →
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes Ask about this →
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0 Ask about this →
Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented) Ask about this →

11 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 0.0 — up to +25.0 composite points Ask about this →
Access Clarity scores 0.0 — up to +20.0 composite points Ask about this →
Developer Ergonomics scores 21.4 — up to +15.7 composite points Ask about this →

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Not sure how this applies to your stack? Ask about any one item. Kin Lane reads every question, looks at your profile and your situation, and replies with what a fix would take — scoped to that one area, priced up front, yours whether you ship it or not. Ask a question →

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/companystack-co-uk/apis.yml: open an issue on github.com/api-evangelist/companystack-co-uk to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Model Context Protocol (MCP)

measured — observed by APIs.io (documented)

APIs 1

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

CompanyStack MCP Server

Remote streamable-HTTP MCP server for UK company data built on Companies House records (search, officers, owners/PSCs, shareholders, filings, filed accounts/financials, new inco...

MCP Servers 1

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

CompanyStack MCP Server

UK company data: search, officers, owners, shareholders, filed accounts, new companies, KYB checks.

MCP SERVER

Security Posture 2

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

CompanyStack Authentication

2 schemes

SECURITY

CompanyStack Domain Security

TLSv1.3 · DMARC

SECURITY

Resources

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

ChangeLog

ChangeLog

Company 1

The organization behind the API

Website

Website

Other 1

Properties that don't map to a standard resource type

Hosts

Hosts

Source (apis.yml)

aid: companystack-co-uk
name: CompanyStack
description: CompanyStack (companystack.co.uk) is a UK company data provider built on Companies House records. Per its official
  MCP Registry entry (uk.co.companystack/mcp, v0.1.1) it offers search, officers, owners/PSCs, shareholders, filings and filed
  accounts/financials, newly incorporated companies and KYB checks, served as a remote streamable-HTTP MCP server at https://api.companystack.co.uk/mcp
  authenticated with a CompanyStack API key (X-Api-Key, cs_ prefix) or OAuth sign-in.
url: https://artifacts.apis.io/companystack-co-uk/apis.yml
x-type: company
x-source: harvest:mcp-registry
x-tier: profiled
x-tier-reason: enrichment pass 2026-11-04 (modular-v1; was harvest)
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  probe_state: unreadable
  source:
  - authentication
  - security
  generated: '2026-11-13'
  method: derived
specificationVersion: '0.20'
created: '2026-11-04'
modified: '2026-11-04'
tags:
- Company
- Company Data
- Companies House
- United Kingdom
- KYB
- Business Verification
- MCP
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
image: https://companystack.co.uk/icon-512.png
common:
- type: ChangeLog
  url: changelog/companystack-co-uk-changelog.yml
- type: Authentication
  url: authentication/companystack-co-uk-authentication.yml
- type: Hosts
  url: hosts/companystack-co-uk-hosts.yml
- type: DomainSecurity
  url: security/companystack-co-uk-domain-security.yml
- type: Website
  url: https://companystack.co.uk/
- type: Documentation
  url: https://companystack.co.uk/developers/mcp
apis:
- aid: companystack-co-uk:companystack-mcp
  name: CompanyStack MCP Server
  description: Remote streamable-HTTP MCP server for UK company data built on Companies House records (search, officers, owners/PSCs,
    shareholders, filings, filed accounts/financials, new incorporations, KYB checks), authenticated with a CompanyStack API
    key (X-Api-Key, cs_ prefix) or OAuth sign-in, as published in the official MCP Registry entry uk.co.companystack/mcp v0.1.1.
  humanURL: https://companystack.co.uk/developers/mcp
  baseURL: https://api.companystack.co.uk/mcp
  tags:
  - Companies House
  - MCP
  - KYB
  properties:
  - type: Documentation
    url: https://companystack.co.uk/developers/mcp
x-coverage:
  state: unreadable
  reason: connection-refused
  detail: companystack.co.uk refused TCP connections on 443 (ECONNREFUSED 161.97.75.63) to curl, a browser UA, fetch-url.py
    render, and WebFetch on 2026-11-04; not a bot challenge. Identity taken from the official MCP Registry entry uk.co.companystack/mcp.
  evidence:
  - url: https://companystack.co.uk/
    status: ECONNREFUSED
  - url: https://companystack.co.uk/developers/mcp
    status: ECONNREFUSED
  - url: https://registry.modelcontextprotocol.io/v0/servers?search=companystack
    status: 200
  checked: '2026-11-04'
x-enrichment:
  date: '2026-11-04'
  status: enriched
  artifacts_added: 10
  pass: modular-v1
  engine: identity=anthropic,contract=anthropic,surfaces=anthropic,docs=anthropic,regulatory=anthropic

CompanyStack API — frequently asked questions

Does CompanyStack have an API?

Yes. APIs.io lists 1 API from CompanyStack, including CompanyStack MCP Server.

How do I authenticate with the CompanyStack API?

CompanyStack uses bearer-token authentication (2 schemes). The details are profiled on APIs.io as CompanyStack Authentication.

Does CompanyStack have an MCP server?

Yes. APIs.io lists 1 MCP server for CompanyStack: UK company data: search, officers, owners, shareholders, filed accounts, new companies, KYB checks.

Is the CompanyStack API ready for AI agents?

CompanyStack has a Kin Score of 11.4 out of 100 (emerging) and an Agent Readiness score of 6.0 (agent-aware), scored by API Evangelist on 2026-11-13.

Work with this as data

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Tools for providers

9 MCP tools reach this

find_providersBrowse and filter every provider in the catalog.
get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

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