get_metric

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

Annotations already declare readOnly/openWorld=false/destructive=false, so safety is covered. The description adds real behavioral context beyond that: variants of the same metric exist under separate IDs, values across variants are not comparable, and variants are only published where a checked quote and reference code exist.

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?

Front-loaded with the core action, then the card contents, then the comparability caveat and the routing sentence. The field enumeration (formula, zone, source, quote, reference code, caveats) is a bit dense but informative rather than 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?

There is no output schema, so the description carries the return-value burden — and it does, describing the card's contents, the variant structure, and the non-comparability caveat. Nothing an agent needs to call this correctly 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?

Schema coverage is 100% and the id description already lists card ID, variant ID, and alias forms. The description reinforces this with concrete examples (ppda.statsbomb-hudl) and adds a usage rule for the parameter ('cite the exact variant ID'), which goes slightly beyond the schema.

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 (read) and resource (a metric card, i.e. one checked definition of a football metric) and enumerates what the card contains. It also names the sibling it is not (list_metrics), so an agent can route correctly without opening schemas.

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 routes browsing to list_metrics and implies get_metric is for retrieving a known card, and warns 'cite the exact variant ID'. It stops short of a full when-not statement (e.g. what to do with an ambiguous name or alias), but the context is clear.

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