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

Annotations declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is already known. The description adds valuable behavioral context: pagination caps, return contents (12 monthly lodging limits, daily M&IE limit, locality/county coverage, source metadata), and the fact that GSA publishes the current three fiscal years. These details go beyond the annotations without contradicting them.

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 description is succinct and well-structured. It opens with the core purpose, then details the input methods, pagination, return contents, and fiscal year caveats. Every sentence contributes useful information without redundancy, and the structure naturally guides the reader from what to how.

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, the description must explain return values, and it does: it lists the monthly lodging limits, daily M&IE limit, locality/county coverage, and source metadata. It also covers fiscal year timing and exclusions. The description is comprehensive for a moderately complex lookup tool, though it could mention potential errors or how pagination works in more detail. Overall, it's complete enough for an agent to use correctly.

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 all six parameters already have descriptions. The tool description adds critical semantic context: the mutual exclusivity of zip versus state+city, the optional nature of city, and the default/maximum limit. It also notes normalization of GSA punctuation quirks for city names. This adds value beyond the schema, justifying a score above the baseline of 3.

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 clearly identifies the tool's purpose: looking up GSA lodging and M&IE rates for a federal fiscal year and CONUS destination. It specifies the exact resource (GSA rates), the data returned, and the input types (ZIP or state+city). It also distinguishes itself from the sibling tool gsa_per_diem_mie_breakdown by focusing on the main lookup rather than a breakdown.

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 provides clear usage instructions: use either a five-digit ZIP or a two-letter state with an optional city, and notes that state-only results are paginated and capped. It also explains the fiscal year definition and explicitly excludes Alaska, Hawaii, territories, and foreign locations, implying this tool is for CONUS only. While it doesn't name alternatives, the scope is well defined.

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