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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds valuable non-obvious semantics: counts count entities, not licences; each company appears once; byClass sums to total; and the regulator's own licence tally will not match. This is exactly the kind of context that prevents misinterpretation.

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 compact, front-loaded with the tool's purpose, then clarifies count semantics, then covers input format and the alternative. Every sentence contributes essential information with 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?

For a single-parameter, read-only tool with an output schema, the description is complete: it explains what the tool returns, the key semantic caveat, accepted input formats, and when to use list_insurers instead. Nothing essential 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 schema already documents the country parameter with slug and ISO alpha-2 examples. The description repeats this format but adds no new meaning beyond the schema, so the baseline 3 is appropriate.

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 and resource: 'Get compact market facts for one country,' and enumerates the included fields while explicitly noting 'without its insurer rows.' This clearly distinguishes it from list_insurers and related market-data tools.

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 the agent: 'Use list_insurers with country for paged entity records.' It also implies this tool should be chosen when only summary facts are needed, and the count-vs-licence warning prevents misuse. This is actionable, decision-ready guidance.

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