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

Annotations already declare a safe read-only, closed-world operation, and the description adds real behavioral context: what the tool returns (size, reasoning in terms of his own shirts, expected fit, confidence) and a strong constraint on how the agent should relay that output. It doesn't address what happens with sparse or contradictory shirt data, so not 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?

Three sentences, each doing work: the capability, the return shape, and the critical output-handling rule, with the core purpose front-loaded. Nothing redundant and nothing padded.

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 tool with a nested schema and no output schema, the description covers both the input basis (his own shirts) and the full return shape (size, why, fit, confidence), plus how to communicate the result. An agent has what it needs to call it and act on the answer.

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 enums and nested fields are already documented; the description only adds the framing that the recommendation is derived from his existing well-fitting shirts and accounts for fabric and cut. That is helpful context but not new per-parameter meaning, 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?

States a specific verb and resource (recommends a size, for one shirt) plus the basis for the recommendation (shirts he already owns that fit). That scope alone separates it from sibling tools like shirt_measurements and what_to_buy, which deal in raw measurements and purchase choice rather than a single size verdict.

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?

Gives an explicit instruction for how to use the result: tell him exactly the size it returns, and do not suggest a different size, with the reason spelled out. It does not explicitly compare itself to the sibling tools or state when this is the wrong tool to reach for, which keeps it below a 5.

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