get_origin_crux

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

With no annotations, the description carries the full burden for behavioral transparency. It discloses that the tool aggregates data across all pages and operates at the origin level, which adds value. However, it does not mention potential limitations such as data availability thresholds, sampling, response format, or error cases. Basic behavior is covered, but not rich contextual detail.

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?

The description is a single, well-structured sentence that front-loads the core action and resource, followed by a practical use case. Every word earns its place, with no redundancy or filler.

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?

The tool is relatively simple (2 params, no nested objects, no output schema). The description provides sufficient context for what it does and when to use it, but lacks explicit guidance on return values or error handling. Given the absence of an output schema, a brief note on what data the agent should expect would make it more complete, but as is it is mostly adequate.

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%, so the baseline is 3. The description reinforces the 'origin' semantics by explaining it as 'entire origin (domain-level)', but does not add significant new meaning beyond the schema's parameter descriptions. The formFactor parameter is already well described in the schema with enum values.

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 clearly states what the tool does: 'Get Chrome UX Report field data for an entire origin (domain-level), aggregating real-user Core Web Vitals across all pages'. It uses a specific verb (Get) and resource (Chrome UX Report origin field data), and distinguishes itself from page-level tools by emphasizing origin-level aggregation and the use case when a single URL lacks traffic.

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?

The description gives a clear when-to-use condition: 'useful when a single URL lacks enough traffic for page-level data'. This implies an alternative (page-level CrUX) without explicitly naming it, but does not provide exclusions or explicit alternatives. Still, the context is clear enough for an agent to decide between this and sibling page-level tools.

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