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

Goes well beyond the readOnly/openWorld annotations: discloses the paid model ($0.002 USDC per successful call via x402 on Base, Solana or Arc), that failed calls are free, and that the data is a community-maintained mirror rather than an official YC API. The cost and provenance disclosures materially affect whether and how an agent calls it.

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

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

Two sentences, front-loaded with the purpose and return fields before the pricing/provenance caveat; nothing is redundant. Slightly dense with stacked field lists, but every clause carries information.

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

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

For a single-parameter read tool with an output schema and annotations present, the description covers what is needed: scope, matching field, payment requirement, and data reliability caveat. An agent can decide to call it and know it will incur a micro-charge.

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

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

Only one parameter (q) and the schema already documents it at 100% coverage including the 2–80 character constraint. The description confirms name-or-slug searching but adds no syntax or matching-behavior detail beyond the schema, so the baseline 3 applies.

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

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

States a specific verb and resource ('Y Combinator startup directory: searches companies by name') and enumerates the returned fields (batch, status, industry, team size, one-liner, website, profile URL). The YC-specific scope makes it immediately distinguishable from generic directories like b2b_linkedin_company_profiles or b2b_techstars_portfolio.

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

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

The query mechanism ('searches companies by name') implies when to use it, but there is no explicit guidance on when to prefer it over siblings such as b2b_techstars_portfolio or b2b_clutch_reviews, and no exclusions or prerequisites beyond the pricing note.

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