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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds ordering semantics ("newest first") and the fact that failed sends and open/download events are included, but says nothing about pagination limits, volume of results, or account scoping beyond "connected account."

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?

Two sentences with the resource and the returned fields front-loaded, no filler. The trailing fragment "Optionally for one product." is clipped to the point of being slightly awkward, but it is efficient rather than redundant.

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 small optional-parameter read tool with full schema coverage and a rich annotation set, the description covers what is needed, especially the returned fields, since no output schema exists. Missing only pagination behavior and a mention of how many records a default call yields.

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 100%, so all three parameters are already documented, including the language enum and the product id reference to list_my_products. The description only adds that product_id is an optional narrowing filter, which the schema already conveys via not being required, so it stays at the baseline.

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 uses a specific verb and resource ("Returns the proof of delivery of the connected account") and enumerates the returned facts: address, document version, send failure, open and download events. It does not, however, name or contrast with any sibling tool, so an agent must infer its place in the catalog.

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?

Usage is only implied: the agent can tell this is a read-only listing of delivery proofs, optionally narrowed "for one product." There is no statement of when to prefer it over something like get_current_document or list_documents_due, and no prerequisites or exclusions are given.

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