diff_profiles

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

No annotations are provided, so the description discloses key behaviors: matching by call-frame coordinates rather than transient node IDs, and normalization against total duration. This adds meaningful transparency beyond schema fields, though it does not cover error handling or return format.

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 tight sentences with no fluff. The purpose is front-loaded, and the second sentence provides valuable detail on matching stability and a concrete use case, earning its place.

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 3 params, no annotations, and no output schema, the description gives the tool's purpose, matching method, normalization, and a concrete question to answer. It lacks a precise structure of the return value, but it is adequate for selection and invocation.

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 descriptions cover all three parameters (100%), including descriptions for before/after paths and top_n. The description reinforces that before is baseline and after is optimized, but does not add extra semantics beyond the schema, so baseline 3 is appropriate.

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 uses a specific verb 'compares' and clearly states the resource (two V8 .cpuprofile files) and the output (per-function CPU time deltas). It distinguishes from sibling profiling tools by emphasizing before/after optimization comparison and stable frame matching.

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?

It provides a direct use-case: 'Use to answer: which functions improved or regressed after my change, and by how much?' This gives clear context for when to use the tool, though it does not explicitly mention when not to use it or name alternative sibling tools.

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