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

Annotations only declare readOnlyHint=false, so the description usefully discloses the pipeline ('Base64 audio → Storage → message-send') and that the backing space is auto-resolved. It says nothing about permissions, size limits, or failure modes, which for a write tool with a 15 MB payload is a real gap; the limit only appears in the schema.

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 tight sentences with the action and target front-loaded and the pipeline detail second. No filler, no restatement of the name.

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?

Covers the core mechanic and resolves the main ambiguity (space_id optional), and no output schema means return values need not be explained. However, for a mutation that uploads binary data, it omits confirmation of what the caller gets back and any constraint beyond the schema's maxLength.

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 86%, so the schema already documents mime, duration_ms, reply_to_id, and the base64/size constraint. The description's 'backing space resolved automatically' echoes the space_id schema description rather than adding new meaning. Baseline 3 applies when the schema does the heavy lifting.

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 ('Send a VOICE note into a persistent channel') and clarifies it lands as a 'first-class `voice` message', which separates it from generic siblings like mIRC_post_message and mIRC_send_file. It does not name the sibling it is NOT (e.g. mDM_send_voice for DMs), so it falls just short of full sibling differentiation.

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?

No guidance on when to choose this over mIRC_send_file, mIRC_post_message, or mDM_send_voice. The only implicit signal is the word 'channel' in the description, leaving the agent to infer the selection criteria from sibling names.

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