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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description still adds real context beyond them: the folder-vs-file branching of the response, the flagging of OCR-recognised text in scanned files, and the underlying API endpoint GET /3/inbox/{Id}.

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?

Front-loads the return behavior and then layers in the file case, usage condition, read-only note and API reference in a compact block with no filler sentences. The trailing API URL is slightly incidental but small enough not to distract.

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 one-parameter read tool with annotations and an output schema, the description covers the essentials, including the non-obvious file branch. The only residual gap is that it never says where valid Ids come from, which matters for a lookup-by-Id tool.

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% with a single documented Id parameter, so the baseline is 3. The description adds useful meaning by showing the Id namespace conventions (inbox_s, inbox_ku) and noting the same parameter may resolve to a file rather than a folder, but it does not explain how Ids are obtained.

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 and resource (returns an inbox folder by Id with its files) and explicitly covers the dual behavior when the Id refers to a file, returning its text. The concrete Id examples (inbox_s for supplier invoices, inbox_ku for receipts) make the resource scope unmistakable and separate it from a folder-listing tool.

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 when-to-use clause: when the person asks what an inbox folder holds or what a file in the inbox says. It does not name alternatives (e.g., list_inbox_folders for discovering Ids) or state when not to use it, so guidance is clear but not exhaustive.

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