Upload attachment chunk

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

The description adds the strict-ordering behavioral constraint, which is not conveyed by the annotations. However, it does not disclose what happens on out-of-order chunks, whether the operation is reversible, or any other side effects beyond the append itself. The annotations already signal mutation and non-idempotency, so the description's incremental value is limited.

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?

A single sentence with no filler, front-loaded with the action verb and the key ordering constraint. Every word earns its place.

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?

The description, combined with the input schema, annotations, and presence of an output schema, gives an agent enough to select and invoke the tool correctly. The main missing context is the explicit relationship to begin_attachment_upload and finish_attachment_upload, but that is strongly implied by the tool's name and sibling list.

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?

With 0% schema description coverage, the description carries the semantic burden and largely succeeds: 'attachment upload' maps to upload_id, 'index order' maps to chunk_index, and 'base64 chunk' maps to data_base64. It compensates for the bare typed schema by tying each parameter to the operation's real-world meaning.

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 ('Append'), a clear resource ('base64 chunk to an attachment upload'), and an important constraint ('strictly in index order'). This clearly differentiates it from sibling tools like begin_attachment_upload, finish_attachment_upload, and discard_attachment.

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 phrase 'next base64 chunk' and 'strictly in index order' strongly imply the tool is used between beginning and finishing an upload. However, it does not explicitly say when to use it versus the sibling tools, nor does it state prerequisites such as requiring an active upload created by begin_attachment_upload.

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