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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds the return shape (passes, fails_by_category, total_cost), which is genuinely useful given there is no output schema, but nothing about cost semantics, result size or ordering.

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 short sentences, front-loaded with purpose and ending with the output shape; nothing is padded. The telegraphic question style and the 'Optional version filter' fragment are the only rough edges.

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 simple two-parameter read tool with annotations and no output schema, supplying the output shape is a real contribution. However, the incorrect 'optional' qualifier on a required parameter and the absence of any routing versus benchmarks_compare leave it only adequate.

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 0%, so the description must explain both parameters, and it actively misleads: it calls version 'optional' while the schema marks it required. The 'given model' wording weakly maps to the model parameter, but the contradiction on a required field is a meaningful defect.

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 question form 'Where does a given model pass/fail?' conveys a specific resource (per-model benchmark pass/fail results) and is reinforced by the output shape naming passes, fails_by_category and total_cost. It is somewhat indirect and does not distinguish this from benchmarks_compare or benchmarks_list, so it stops short of a 5.

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?

'Optional version filter' is the only usage hint, implying the tool is scoped to one model. There is no explicit when-to-use versus the sibling comparison/list tools, and no mention of prerequisites such as needing a known model identifier.

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