search_companies

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

With no annotations, the description carries the full burden and does disclose the result cap (up to 20 matches) and the returned fields (company_number, name, status, R-Score). It omits matching behavior (exact vs. fuzzy) and any auth or rate-limit considerations, so it is good but not exhaustive.

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?

Three short sentences, each earning its place: what it does, when to reach for it, and what comes back. The routing guidance is front-loaded immediately after the purpose.

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 no output schema and no annotations, the description usefully covers the return fields and the 20-match cap. It stops short of explaining name-matching behavior or what happens when more than 20 companies match, which an agent would want to know.

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 0%, so the description must carry the parameter meaning. "Search UK companies by name" establishes that query is a company name, but it adds no detail on matching semantics, minimum length, or formatting, leaving a gap for a single required parameter.

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 (Search) and resource (UK companies) plus the goal of retrieving a Companies House number. This cleanly separates it from get_company, which takes a number rather than a name.

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 this first when the user gives a company name instead of a number" gives an explicit trigger condition and implies the number-based alternative without naming get_company. No exclusions or edge cases (e.g., ambiguous or partial names) are given, so it falls short of a full 5.

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