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

No annotations are provided, so the description carries the full burden, and it does substantial work: it discloses the response shape (per-month lodging rate plus daily M&IE rate), the fiscal-year boundary definition, case-insensitive partial matching, and what `verification_url` adds. It stops short of pagination, ordering, or behavior when the state/year combination has no data.

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?

The scope statement is front-loaded and the follow-on sentences each add information (return shape, fiscal-year definition, filter behavior). There is mild redundancy between the title line and the first body sentence, and the fiscal-year explanation is repeated in the schema, keeping it off a 5.

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 no output schema and no annotations, the description is the only place the return shape is explained, and it does explain it (monthly lodging + daily M&IE). Combined with the fiscal-year definition, an agent can call this correctly; only edge-case behavior (empty results, ordering) 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 description coverage is 100%, so every parameter is already documented in the schema, including the fiscal-year definition, partial-match semantics, and the verification_url effect. The description restates rather than extends that, so the baseline 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?

The description opens with a specific verb+resource ('GSA per diem rates by state and fiscal year') and the first body sentence pins the scope: every GSA destination rate in a state for a US fiscal year. That distinguishes it from get_gsa_perdiem_by_state (no year) and get_gsa_perdiem_by_destination, but it never names those siblings, so the agent must infer the boundary.

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 only implied by the scope statement and by the optional `location` filter. There is no explicit 'use this when you need all destinations in a state' versus 'use get_gsa_perdiem_by_state for the latest year' guidance, and no mention of prerequisites or error conditions.

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