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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds useful behavioral context: it reads from public advanced-search results, targets active companies, defaults to a 60-day window, and includes cost/payment details ($0.02/call, x402 USDC). This goes beyond the annotations and helps the agent understand side-effect-free access and potential rate/cost implications.

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 two sentences, front-loaded with the core purpose, and includes only essential details (data source, defaults, access constraints, pricing). Every sentence adds value, with no redundancy or fluff. It is highly scannable for an AI agent.

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 100% schema coverage and default values for windowDays (60) and maxConcurrency (5), the description provides enough context for invocation. However, since there is no output schema, a brief mention of the expected return format (e.g., company records with name, incorporation date) would improve completeness. Still, the description covers the essential inputs and access constraints, making it adequate for selection and basic usage.

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?

The input schema has 100% parameter description coverage, with each parameter (items, windowDays, maxConcurrency) clearly explained. The description does not add significant new parameter semantics beyond the schema, but it provides context about the default window ('~60 days') and the data source, which slightly enriches understanding. Baseline 3 is appropriate because the schema carries the parameter documentation burden.

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 the tool's purpose: 'Find newly-incorporated UK companies matching a keyword' with a specific data source (Companies House public advanced-search) and a specific scope (active companies, ~60 days). This distinguishes it from sibling tools like company-lookup or company-registry-enricher by focusing on new incorporation detection.

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 implies when to use the tool (when you need newly incorporated UK companies matching keywords) and mentions that it requires no API key, login, or proxies, which sets expectations for access. It does not explicitly contrast with alternatives, but the scope is clear enough for an agent to select it appropriately among siblings.

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