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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, yet the description still adds real value: the data provenance (software stacks on Proven, ~2,700 companies), the ranking key (companies_using), the accompanying fields (Proven Score, deal), and the constraint that companies are never named. It doesn't cover result-size behavior or freshness, keeping it below 5.

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?

Three sentences, front-loaded with what the tool measures, then when to use it, then what comes back. The opening sentence is dense with parentheticals but every clause carries information; nothing is padding.

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?

With no output schema, the description correctly takes on the burden of describing the return shape (ranked by companies_using, with Proven Score and deal) and privacy behavior. For a three-optional-parameter read tool this is nearly complete, though the meaning of 'deal' is left unexplained.

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?

Schema coverage is 100%, so the schema already documents need, limit (default 8, max 15) and category. The description's job examples loosely mirror the 'need' parameter but add no new guidance on how to phrase or scope it. Baseline 3 is appropriate.

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?

The description names a specific resource (vendors startups actually use) and a specific measure (companies_using counts derived from ~2,700 portfolio companies' stacks), which is enough to distinguish it from a generic vendor lookup or comparison tool. It does not name a sibling to contrast against, so it falls short of a 5.

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?

It gives a clear triggering scenario ('when someone building a product asks which provider to pick') and enumerates example jobs (auth, database, email API, payments, error monitoring, CRM). There is no explicit when-not-to-use or named alternative such as find_vendors or compare_vendors, so the guidance is contextual rather than exclusionary.

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