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

Annotations already cover readOnly/idempotent/non-destructive/openWorld, so the bar is lower. The description adds real operational context: coverage scope, once-a-day refresh surfaced via data_as_of, and that status defaults to EVERY status rather than 'posted'. It omits return-shape and paging behavior, keeping it just shy of a 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?

A single dense paragraph that front-loads scope and the sibling contrast before listing filters and example questions. Every sentence carries differentiating 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?

For an 11-param read-only search with no output schema but full schema coverage, the description supplies the coverage boundary, staleness signal, default behavior, and filter set an agent needs to call it correctly and interpret freshness.

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%, so the schema already documents all 11 parameters, including the status default and keyword matching behavior the description restates. The description adds little syntax or format detail beyond the schema, so the baseline 3 is correct.

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?

Specific verb+resource with explicit scope: 'Grants.gov's FULL opportunity history (closed and archived back to 2004, plus forecasted)'. It directly contrasts with the sibling search_opportunities and the search2 live API, so an agent can distinguish the two without opening either 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?

States when to use it ('what did this agency fund last fiscal year', 'what under CFDA 93.351 has ever closed', 'what is forecasted but hasn't posted') and when the sibling is better ('search2 only usefully answers what is open right now'). It even flags the default-status divergence that would otherwise cause a wrong call.

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