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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, non-destructive), so the bar is lower. The description adds genuine value beyond annotations by disclosing that the API is keyless and by enumerating the return fields (opportunity number, title, agency, status, open/close dates, CFDA numbers), which orients the agent on what results look like. No contradictions with annotations.

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 with zero waste: first sentence states purpose and keyless access, second sentence enumerates filters and return fields. Everything earns its place, and the core action is 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?

For a read-only search tool with 7 optional parameters, the description covers the domain origin, filter capabilities, and return fields (partially compensating for the missing output schema). The only notable gap is the lack of an explicit pointer to grants_get_opportunity for fetching full opportunity details, which would complete the navigation story.

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% — all 7 parameters have meaningful schema descriptions including default values and pipe-separated syntax. The description summarizes these filters but adds no genuinely new semantics beyond what the schema already documents, so the baseline score of 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 ('Search federal funding opportunities on Grants.gov') plus the keyless qualifier, and lists concrete filter dimensions and return fields. This clearly positions it as the discovery tool and distinguishes it from the sibling grants_get_opportunity, which presumably retrieves a single opportunity's details.

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 description establishes clear usage context — searching for funding opportunities with filters, and the keyless note signals no auth setup is needed. However, it never explicitly names the alternative (grants_get_opportunity) or states when not to use it, so the agent must infer the search-vs-detail split from sibling names alone.

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