Server Quality Checklist

Tool Scores

• crux_compareA
  4.2/5.0
  Behavior4/5

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

  Annotations already declare the tool read-only, open-world, idempotent, and non-destructive. The description adds valuable behavioral details: returns one row per origin, includes pass/fail status, and reports origins without CrUX records rather than silently dropping them. This goes beyond annotation cues.

  Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

  Conciseness5/5

  Is the description appropriately sized, front-loaded, and free of redundancy?

  The description is compact and well-structured: it opens with purpose, then explains input format, and closes with output behavior. Every sentence carries meaningful information without redundancy or fluff.

  Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

  Completeness4/5

  Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

  With an output schema present, the description need not explain return structure. It adequately covers purpose, input format, and edge-case handling for missing data. A brief mention of form_factor would improve completeness, but the current level suffices for a moderately simple comparison tool.

  Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

  Parameters3/5

  Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

  The description thoroughly explains the 'origins' parameter with a comma-separated format and a concrete example, which is critical since schema descriptions are absent. However, 'form_factor' is not documented in the description, and the schema only provides a default. Partial compensation for a 0% schema coverage.

  Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

  Purpose5/5

  Does the description clearly state what the tool does and how it differs from similar tools?

  The description clearly states the tool compares Core Web Vitals across multiple origins, using a specific verb ('compare') and resource ('Core Web Vitals'). This distinctly separates it from siblings like crux_record (single origin) and crux_history (time series).

  Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

  Usage Guidelines4/5

  Does the description explain when to use this tool, when not to, or what alternatives exist?

  The phrase 'several origins — yours against competitors' implies the intended comparison use case. It does not explicitly name alternative tools or exclusion conditions, but the contrast with sibling tool names and the context of competitor benchmarking provide strong guidance.

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

• crux_historyA
  4.2/5.0
  Behavior4/5

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

  Beyond the annotations (readOnly, idempotent, non-destructive), the description adds useful behavioral details: a maximum of 25 data points, weekly granularity, and that passing a metric returns a single series. This enriches the agent's understanding without contradicting the annotations.

  Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

  Conciseness5/5

  Is the description appropriately sized, front-loaded, and free of redundancy?

  The description is compact and front-loaded, with the core purpose in the first sentence and additional parameter details in the second. Every sentence earns its place, with no redundant or extraneous information.

  Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

  Completeness4/5

  Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

  Given the presence of an output schema and standard parameters, the description covers the essential aspects: what the tool returns (trend over time), key constraints (25 points), and how to filter by metric. It relies on the 'same rules as crux_record' reference, which is a minor gap but acceptable given sibling tool availability.

  Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

  Parameters3/5

  Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

  Schema description coverage is 0%, so the description must compensate. It thoroughly explains the 'metric' parameter with concrete examples, but only references 'same rules as crux_record' for url/origin/form_factor, requiring the agent to consult a sibling tool for full semantics. This is helpful but not fully self-contained.

  Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

  Purpose5/5

  Does the description clearly state what the tool does and how it differs from similar tools?

  The description clearly states the tool's function: 'Weekly Core Web Vitals trend, up to 25 points, for charting or regression checks.' It uses a specific verb (trend) and resource (Core Web Vitals), and distinguishes itself from siblings by focusing on history/trend rather than single records or comparisons.

  Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

  Usage Guidelines4/5

  Does the description explain when to use this tool, when not to, or what alternatives exist?

  The description provides clear context for when to use the tool ('for charting or regression checks') and notes the same filtering rules as crux_record. However, it does not explicitly indicate when NOT to use it or directly compare with crux_compare, leaving some room for interpretation.

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

• crux_recordA
  4.4/5.0
  Behavior4/5

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

  Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds useful context about the return format (p75 with assessments, core_web_vitals_pass) and the raw=true option, which are not stated in the schema. No contradictions found.

  Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

  Conciseness5/5

  Is the description appropriately sized, front-loaded, and free of redundancy?

  The description is two compact paragraphs with a clear opening statement followed by necessary parameter and output details. Every sentence adds value, with no filler or repetition, and it is appropriately front-loaded.

  Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

  Completeness5/5

  Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

  Given the 4 optional parameters and existing output schema, the description covers all key aspects: how to specify origin vs url, form_factor options, raw flag, and what the response contains. It is sufficient for correct invocation without additional external documentation.

  Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

  Parameters5/5

  Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

  With 0% schema description coverage, the description fully compensates by explaining all four parameters: origin/url mutual exclusivity, form_factor allowed values, and raw behavior. It adds meaning beyond the schema's type/default details.

  Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

  Purpose5/5

  Does the description clearly state what the tool does and how it differs from similar tools?

  The description clearly states the tool returns 'Current p75 Core Web Vitals for an origin or a single URL' with a specific resource (CrUX data) and scope (origin or URL). It distinguishes itself from siblings via 'current' and explicit mention of the metrics and pass/fail assessment.

  Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

  Usage Guidelines3/5

  Does the description explain when to use this tool, when not to, or what alternatives exist?

  The description gives clear guidance on parameter usage ('Pass EITHER origin OR url') and form_factor values, but does not explicitly mention when to use this tool versus alternatives like crux_history or crux_compare. Usage context is implied ('current') but not contrasted with siblings.

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