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

Adds substantial context the annotations do not carry: the upstream API, a metered price of $0.002 USDC per successful call, accepted payment rails (x402 on Base, Solana, Arc), and that failed calls are not charged. Safety is already covered by readOnlyHint/openWorldHint, so the remaining gap is minor (no rate limits or freshness/caching behavior).

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 dense sentences: identity and fields first, scope exclusion second, cost last. No filler, and the most decision-relevant facts (source, fields, not-awards, price) are front-loaded.

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 an output schema present, the description needn't detail return values, and annotations cover read-only/open-world semantics. It fills the remaining gaps an agent needs — provenance, scope boundary, and billing model — for a two-parameter search tool.

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 description coverage is 100% and both parameters (keyword length bounds, limit 1-10 with default 5) are documented in the schema itself. The description adds nothing about how the keyword is matched (full-text, phrase, fuzzy), so it cannot rise above the baseline.

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 resource (US federal grant opportunities from the Grants.gov search2 API), enumerates the returned fields (opportunity number, title, agency, open/close dates, status, CFDA numbers), and explicitly bounds the scope with 'Opportunity listings only, not award decisions'. That boundary alone lets an agent separate it from award/contract tools such as gov_government_contract_awards without opening a schema.

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?

Usage is clear from the keyword-driven framing plus the explicit exclusion of award decisions, which is a genuine when-not signal. However, it never names an alternative for adjacent needs (e.g. SBIR-specific grants, EU funding, contract award lookups), so the agent must infer routing from the sibling list.

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