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

Annotations only declare readOnlyHint and openWorldHint, but the description adds substantial behavioral context the agent could not infer: a metered cost of $0.002 USDC per successful call via x402 (Base, Solana or Arc), that failed calls are not charged, and that keyword matching spans the full listing rather than just the title. These materially affect invocation decisions.

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?

A single dense paragraph with purpose front-loaded and no filler; the output-field list and pricing clause each carry weight. It is slightly long, but every clause either scopes the result set or disambiguates behavior.

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 explain return values, yet it still names key fields and sorting, and it covers the defaults, matching scope, and billing model. For a 3-parameter read-only search tool, nothing an agent needs to call it correctly is missing.

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 baseline is 3, but the description adds real meaning beyond the schema: it explains how 'q' is interpreted ('matches keywords anywhere in the full listing, not only the title'), which changes query phrasing, and notes the default status set. Date format and sort order are surfaced as output expectations.

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+resource+source: federal grant opportunities from Grants.gov matched by keywords, with the returned fields enumerated (number, title, agency, dates, status, link). 'US federal' and 'Grants.gov' cleanly separate it from the eu_tenders sibling even without naming it.

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 implied by 'matching keywords' plus the stated default of posted and forecasted opportunities, so an agent can tell when a plain keyword query is appropriate. However, no explicit when-to-use/when-not guidance or pointer to the nearest alternative (eu_tenders) is given, leaving routing to inference.

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