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

Beyond the readOnlyHint/openWorldHint annotations, it discloses genuinely useful behavior: nothing is stored, and the output is a physical letter the user must print, sign and post with a hard deadline. It stops short of describing the letter's format or length, so it is not fully rich.

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 tight sentences, front-loaded with purpose and then the operational workflow. Each sentence carries useful content with little waste, though the deadline detail could arguably live in a dedicated deadline tool.

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 10-parameter tool with no output schema and 40% schema coverage, the description covers the workflow and storage behavior but omits guidance on the five optional address/identity parameters. An agent can call it, but not optimally.

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 only 40% across 10 parameters, so the description must compensate and only partially does. It clarifies the kind enum (cancel vs change) and the change-only fields (new_franchise, new_model), but leaves street, postcode_town, insurance_number, insurer_address and birth_date unexplained.

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 (Write/draft) and a concrete resource (the German Kündigung letter) and even names the two modes (cancel vs. change deductible/model). It is clearly distinguishable from siblings like compare_insurance or switching_deadlines, though it does not name those siblings explicitly.

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 gives actionable context (print, sign by hand, post so it arrives by 30 November) but never states when to reach for this tool versus alternatives such as compare_insurance or switching_deadlines. Usage is implied rather than guided.

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