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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint as false, providing a strong behavioral baseline. The description adds valuable context about pricing per call and account-level discounting, which is not in annotations. However, it doesn't describe pagination behavior beyond what's hinted in the schema description for offset.

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?

Four sentences, front-loaded with the core purpose, then usage guidance and pricing. Every sentence adds value with no redundancy. Extremely efficient.

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?

Given the tool's moderate complexity (3 params, simple return), existing annotation coverage, and complete schema documentation, the description is fully adequate. It covers purpose, usage rules, behavioral traits (pricing), and relationships to siblings. The output schema exists but is not shown here, so no need to describe return values.

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% with three parameters fully described (q, limit, offset). The description adds minimal semantic value beyond listing some return fields. Baseline 3 is appropriate since the schema already does the heavy lifting.

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 it searches the UK Companies House register by name or keyword, listing specific return fields. It distinguishes itself from siblings by explicitly mentioning what not to use it for when a company number is known, and names alternative tools (company_uk_profile, company_uk_status).

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 explicitly states when to use ('Look up a UK company by name'), when not to use ('You already have the company number'), and provides clear alternatives. This level of guidance is exemplary.

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