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 ({a_only_passes, b_only_passes, both, neither}), which is genuine extra context, but it never explains what a 'pass' is or which benchmark set the version scopes to.

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 lines with no padding, and the output shape is easy to scan. But the brevity comes from under-specification rather than tight writing, leaving the agent without operational detail.

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?

There is no output schema and no parameter documentation, so the description carries the full explanatory burden for a three-required-param comparison tool. It supplies only the output key names, missing input format, version semantics, and how the comparison is derived.

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% across three required parameters, so the schema provides only names and types. The description does not clarify what modelA/modelB should be (IDs vs names) or what 'version' refers to, so it fails to compensate for the coverage gap.

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?

"Pairwise model comparison" names the resource and the operation, so an agent knows it compares two models. However, it doesn't say what is being compared (benchmark pass results) or how it differs from siblings like benchmarks_for_model or benchmark_run, leaving the agent to infer the distinction.

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?

There is no when-to-use guidance, no mention of alternatives, and no exclusions. The agent must guess whether to call this or benchmarks_for_model when it wants per-model numbers versus a side-by-side diff.

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