perf_advice

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

Annotations already establish read-only, idempotent, non-destructive behavior; the description goes further by revealing that results are advisory, ranked by impact, and include locations and concrete design fixes. It also discloses the noisy failure mode when misused, adding meaningful context beyond the annotation flags.

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 cover usage, output, and limitations with no repetition or fluff. The most important instruction ('Call ONLY when ...') is front-loaded. Excellent balance of brevity and information.

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 one self-documenting parameter and strong annotations, the description covers the essential output format (ranked constructs with locations and fixes) despite lacking an output schema. It also provides critical operational context (noisy outside performance, language limitations). Nothing needed for an agent to decide to call and interpret results is missing.

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?

The schema already documents the single `profile` parameter fully, including its enum values and default, giving 100% coverage. The description does not add parameter-specific detail, which is acceptable but not additive. Baseline 3 is appropriate since the schema carries the full semantic load.

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: it returns performance-impacting constructs with locations and fixes, and is explicitly advisory rather than scored. It clearly distinguishes itself from sibling analysis tools by limiting itself to performance questions and noting noise otherwise.

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?

Explicitly directs when to call: 'Call ONLY when the user asks about performance' and warns that it is 'noisy otherwise.' It adds a language constraint (tuned for Rust, other languages give limited signal) that helps avoid wasted calls. It does not name alternative sibling tools, but the when/when-not boundary is unmistakable.

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