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

The description goes beyond the readOnly/openWorld/idempotent annotations by disclosing important behavior: how satisfaction is represented (not a separate 'release' record), which flags and particulars are included, and the relationship to company_profile.has_charges. This provides valuable interpretive context for an AI agent using the data.

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 concise and front-loaded with the primary action, but it includes a few explanatory clauses that could be slightly tightened. Overall, each major piece (scope, return contents, satisfaction quirk, usage condition) earns its place and no redundant filler remains.

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 input schema fully documents the parameter and an output schema exists, the description supplies all necessary invocation context plus enough semantic detail about the content. The tool is a straightforward read, and the description fully covers whether/how it relates to other tools.

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 already describes the sole parameter completely (Companies House company number, max length, format). The description adds no additional parameter detail, so with 100% schema coverage, a baseline 3 is appropriate; no value is added beyond the schema.

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 opens with a specific verb and resource: 'Fetch the complete Companies House charge history for a company.' It clearly differentiates itself from siblings by clarifying it covers specific charges rather than a summary, and explains what data is returned (status, dates, secured parties, flags). The distinction from company_profile.has_charges is explicitly named.

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?

It provides an explicit usage condition: 'use this tool when the specific charges matter, not just whether any exist.' This implies an alternative for checking existence (company_profile.has_charges). While it names the summary field rather than the sibling tool directly, the alternative is clear enough for an agent to route correctly.

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