matrix_send_file

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

With no annotations, the description carries the full behavioral burden. It does disclose the msgtype 'auto' inference rule and that a dry run is possible, which is genuinely useful, but it omits permission/size limits on uploads, what dry_run actually returns, and the role of idempotency_key for a mutating send.

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 short sentences, front-loaded with the core action and followed by the two most non-obvious parameter notes. Nothing is padded, though the fragment 'dry_run-able' is terse to the point of being cryptic.

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?

An output schema exists so return values needn't be described, and the msgtype inference is covered. However, for an 8-parameter mutation tool with zero annotation and schema-description coverage, the missing explanation of idempotency_key, tenant scoping, and dry_run behavior leaves real gaps.

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 coverage is 0%, so the description must compensate and it only covers three of eight parameters: file_b64's base64 encoding, msgtype's 'auto' inference against mime_type, and a passing mention of dry_run. tenant, idempotency_key, room_id, and filename receive no explanation at all.

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 a specific verb and resource: 'Send a file attachment to a room,' which clearly distinguishes it from a text-sending tool. It does not name the sibling matrix_send_message or explain the boundary between the two, so a 5 is not warranted.

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 implied (use this when you have file bytes to post), and 'dry_run-able' hints at a preview path, but the description never states when to prefer this over matrix_send_message or what preconditions exist. No exclusions or alternatives are given.

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