ReftrixMCP

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

Annotations declare readOnlyHint, idempotentHint, and openWorldHint. The description adds valuable behavioral context beyond these: the specific measurement methodology ('via Playwright PerformanceObserver API'), the grading scale ('score 0-100, grade'), and the specific metrics included. It does not contradict annotations.

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 sentences with zero waste. First sentence front-loads the action, technology, and target metrics. Second sentence efficiently covers return value structure. Every word earns 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?

Despite lacking an output schema, the description compensates by detailing return values (score range, grade, recommendations). Combined with 100% input schema coverage and complete annotations (readOnly, idempotent, openWorld), this provides sufficient context for invoking the 3-parameter tool, though it could note network dependency implications of openWorldHint.

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%, fully documenting all parameters including nested budget fields. The description mentions 'optional improvement recommendations' which loosely corresponds to the include_details parameter, but adds no semantic detail, syntax guidance, or examples beyond what the schema already provides. Baseline 3 appropriate for high coverage.

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 states a specific action ('Evaluate') and resource ('web page performance using Core Web Vitals') and lists exact metrics (LCP, FID, CLS, INP, TTFB). This clearly distinguishes it from siblings like quality.evaluate (generic quality assessment) and accessibility.audit (accessibility focus).

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?

While the description explains what the tool returns (score, grade, recommendations), it provides no explicit guidance on when to choose this over similar analysis tools like page.analyze or quality.evaluate. Usage is implied but not contextualized against alternatives.

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