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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds non-annotation context: the 'basis' field meaning (stored sampling density, 'never overstated') and per-metric availability for series vs chart rendering. It does not discuss pagination or cost, but this is a static catalog, so little is missing.

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, front-loaded with the action and its routing hint, then the payload contents. The second sentence is a dense enumerated list but every item earns its place by describing a real catalog field; slight compression possible but no 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?

With an output schema present, return values need no prose, and the annotations carry the safety profile. The description still supplies the routing context, field semantics, and resource alternative an agent needs to call this correctly. Nothing material 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 description coverage is 100% and the single enum parameter's trade-off (json vs. markdown token cost, structuredContent always full JSON) is fully documented in the schema. The description never mentions 'format', so it adds nothing beyond the schema; baseline 3 is correct.

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+resource ('The full metric catalog') and enumerates exactly what the catalog contains (slug, label, unit, basis, methodology, availability flags). It also names the two downstream siblings (get_metric_series, get_chart) that consume the slug, so an agent can place it precisely in the tool graph.

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?

'Use to find the right metric slug before get_metric_series or get_chart' gives an explicit trigger condition and names the alternatives it precedes. Also notes the equivalent resource tgmcharts://metrics, so the agent knows it can read the same data without an extra call.

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