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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: listings are company-provided and unverified, they are not an offer, the featured flag means the 3 most recently approved live listings, and unknown arguments are rejected. Data-provenance and argument-strictness caveats are exactly the kind of value the description should add.

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?

The purpose and the field list are front-loaded, and the disclaimers earn their place. However, the closing 'Argument: featured_only (optional boolean: only the 3 featured listings)' largely duplicates the input schema, and the sentence is a dense run-on. Efficient in substance but slightly redundant.

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 compensates by enumerating the returned fields (name, website, one-liner, stage, country, target raise, featured flag) and flagging that target raise is 'never converted.' Annotations cover the safety profile. Combined, this is nearly complete for a read-only single-parameter list tool, missing only usage routing.

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% for the single optional boolean, so the baseline is 3. The description adds meaning beyond the schema by explaining what 'featured' actually denotes (the 3 most recently approved live listings), which resolves the ambiguity of the flag rather than merely restating it.

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 states a specific verb (list) and a tightly scoped resource: fintech companies that pitched Builders in Fintech and opted into a public listing while raising. It goes on to enumerate the exact fields returned, so an agent knows precisely what this yields. It does not explicitly differentiate itself from adjacent siblings like list_funding_rounds or largest_rounds, which keeps it from 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?

There is no when-to-use, when-not-to-use, or named-alternative guidance. An agent must infer from the niche scope that this is for surfacing opt-in public listings rather than general funding data. Nothing routes it against the many sibling funding tools.

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