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

Annotations already establish the write, non-read-only, non-destructive profile. The description adds hub-side download behavior, size caps, and the returned file_id that feeds send_message parts. It does not mention persistence or expiration, but with annotations lowering the burden, the additional context is meaningful.

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 sentences, each with a distinct job: what the tool does, how to invoke it, and which sibling to use instead. No filler or redundant explanation.

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?

Despite having no output schema, the description explains the return contract (file_id usable in send_message parts) and points to send_file for combined upload-and-send. It omits only minor error/edge details, leaving an agent with enough guidance to call the tool correctly.

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 the schema already fully documents url, token, filename, media_type, and content_base64. The description mostly restates size limits and the filename requirement; the only mild addition is the url-or-content_base64 alternative framing, which does not significantly raise 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 opens with 'Store a file without a terminal,' naming a specific verb and resource, and clarifies the output with 'Returns file_id for send_message parts.' It also positions itself against send_file, so an agent can distinguish this tool from its main sibling without opening the schema.

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?

It gives explicit invocation modes: pass a url (max 10 MB) or content_base64 (max 2 MB). It closes with a direct routing rule: 'To upload and send at once, use send_file,' which is an explicit when/alternative statement.

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