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get_histogram

Obtain histogram buckets for a chosen web vital metric (LCP, INP, CLS, FCP, TTFB) with optional filters by device, CMS, CDN, framework, or provider.

Instructions

Distribution buckets for one CWV (or technique metric) under an optional filter.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
filterNo
metricYeslcp | inp | cls | fcp | ttfb, or a contract scalar path
Behavior1/5

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

No annotations provided, so the description must convey behavioral traits. It does not mention read-only, destructive actions, authentication needs, rate limits, or any side effects. This is a critical gap.

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

Conciseness4/5

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

The description is a single, concise sentence. While it could include more detail on behavior, it is efficiently written and front-loaded with the key purpose.

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

Completeness2/5

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

Given the absence of annotations and output schema, the description is insufficient. It does not explain the return value structure, required permissions, how the filter interacts, or example usage. The tool's full context is not provided.

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

Parameters2/5

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

Schema description coverage is only 50% (metric has a brief enum-like description; filter properties have none). The description adds 'CWV (or technique metric)' and 'optional filter' but does not clarify the filter's subfields or value formats.

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

Purpose4/5

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

The description clearly indicates the tool returns distribution buckets for a specific CWV or technique metric, and mentions an optional filter. It differentiates from siblings like get_metrics (likely raw values) and list_options (available choices), but does not explicitly state this distinction.

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

Usage Guidelines2/5

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

No guidance on when to use this tool over alternatives (e.g., get_metrics). The description implies it's for histograms, but lacks explicit context or exclusion criteria.

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

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