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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the description is not carrying the safety burden. It still adds real value beyond them: unfilled fields remain as bracketed placeholders and 'Nothing is stored', which tells the agent about output shape and the absence of persistence — neither is derivable from the annotations.

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, front-loaded with what the tool returns, then the placeholder contract, then the no-storage guarantee. No filler and nothing repeated from the schema or annotations.

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, the description correctly compensates by describing the return value (a plain-text letter plus where to send it). It does not cover failure behavior for an unknown slug, but for a simple read-only generator with one required parameter, the coverage is nearly complete.

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 100%, so the baseline is 3. The description goes one step further by explaining what happens to the two optional parameters when omitted — they appear as [bracketed placeholders] rather than failing or being silently dropped, which is behavior the schema does not state.

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 states a specific verb+resource: it produces a plain-text cancellation letter for one company, plus the mailing address. It distinguishes itself implicitly from get_cancellation_guide (letter vs. guidance) and from search_companies (slug lookup) but never names those siblings, so the separation is left to inference.

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?

There is no explicit 'use this when...' guidance and no named alternative. The closest signal is the schema's slug description pointing at search_companies, which lives in the schema, not the description. An agent must guess whether to call this or get_cancellation_guide first.

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