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

Annotations already cover read-only, idempotent and non-destructive behavior, so the bar is lower. The description still adds real value: it discloses that a computed `status` is derived from close/archive dates against today using the same vocabulary as search_historical_opportunities, plus a `data_as_of` freshness field — genuinely useful given there is no output schema.

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, zero waste. The core scope claim (ANY status) is front-loaded, and the comparison and return-value details follow in a tight secondary clause.

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 only one fully documented parameter and no output schema, the description compensates by describing the return payload (full record plus computed `status` and `data_as_of`). An agent has everything needed to call it and interpret the result.

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% and the schema description already explains the ID is numeric and where it comes from (the `id` field of the search tools). The description's phrase 'numeric opportunity ID' merely restates that, adding no syntax, range, or format detail beyond the schema.

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 (Fetch) and resource (one Grants.gov opportunity) with an explicit scope qualifier: ANY status, enumerating open/closed/archived/forecasted. It also names the sibling get_opportunity and the exact axis of differentiation (live API vs. historical resolution).

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?

Explicitly routes the agent: use this one for non-open/historical lookups; get_opportunity only reliably resolves currently-open opportunities. The when-to-use alternative is stated rather than implied, so selection between the two siblings is deterministic.

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