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

Annotations already cover the safe-read profile (readOnly, idempotent, non-destructive, closed-world), and the description adds real semantic context beyond them: the per-letter status vocabulary, EUR currency on monetary values, and the caveat that provider acceptance is not delivery. 'Nothing is sent' reinforces the absence of side effects.

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?

Dense and front-loaded: the read action and returned fields come first, then the cautionary usage rules. Slightly telegraphic phrasing, but every clause carries information.

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 compensates by enumerating the returned fields and status values, and it covers the retry-hazard context an agent needs. Nothing essential for calling this correctly is missing.

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%, but there is only one parameter and 'waveId' is self-evident; the description ties the read to 'the same tenant letter wave', implying the ID scopes to a tenant's wave. It adds little beyond the schema field name, so a baseline 3 is appropriate.

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 (Read) and resource (tenant letter wave), then enumerates the returned content: exact texts and recipients, revision, totalCents in EUR, and per-letter status. It is clearly distinguishable from mutation siblings like prepare_letter_wave and quote_letter_wave, though it never names a sibling 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?

Gives an explicit trigger ('Read after uncertain mutations') plus a hard prohibition with its rationale ('never recreate a wave to retry a possibly submitted letter'), which steers the agent away from the wrong sibling tools under exactly the condition where confusion is likely.

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