SiteCheck Company Records

Y Combinator startup directory: searches companies by name

b2b_y_combinator

Read-only

Y Combinator startup directory: searches companies by name and returns batch, status, industry, team size, one-liner, website and YC profile URL. Community-maintained open mirror of YC's public company list; not an official YC API. Price: $0.002 in USDC per successful call, paid with x402 (Base, Solana or Arc); failed calls are not charged.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "q": "<q>"
    },
    "name": "b2b_y_combinator"
  }
}

Input Schema

Name	Required	Description	Default
`q`	Yes	Company name or slug, 2 to 80 characters

Output Schema

Name	Required	Description	Default
`count`	No
`query`	No
`source`	No
`results`	No
`dataAsOf`	No
`checkedAt`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 23, 2026

TDQS

A3.7/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare read-only and open-world, so the description isn't burdened with the safety profile. It adds genuinely useful behavior beyond them: the source is a community-maintained mirror, not an official YC API, and calls are metered at $0.002 USDC via x402 on Base/Solana/Arc with failed calls uncharged — important cost and auth context an agent needs before calling.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with what the tool does and what it returns, followed by provenance and pricing. It is dense but every clause carries information; minor tightening of the pricing sentence would help.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The output schema means return values need no explanation, and annotations cover read-only/open-world behavior. The description fills the remaining gaps an agent would care about — data provenance and per-call cost — leaving only matching semantics (exact vs fuzzy) unaddressed.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With a single parameter at 100% schema coverage, the schema already documents 'q' as company name or slug with a 2–80 character range. The description restates name-based searching and adds nothing about slug matching, partial matching, or result limits, so it sits at the baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('searches companies by name') and enumerates the returned fields (batch, status, industry, team size, one-liner, website, YC profile URL). The scope is unambiguous and clearly distinct from registry-style siblings such as b2b_techstars_portfolio or the national company registers, though it never names an alternative outright.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: the tool is for finding YC-backed companies by name. There is no statement of when to prefer it over other startup or company-lookup siblings, nor any exclusion such as 'does not cover non-YC companies' or 'name only, not keyword search'.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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