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

Annotations only declare readOnlyHint=false, so the description carries the disclosure burden and does it well — it states the bytes are uploaded to Storage unsealed until the seal step ships, which is critical safety context. It does not cover permissions, size-limit failure behavior, or what the response returns, but the encryption caveat is genuinely valuable.

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 tight sentences, front-loaded with the core action and scope, then mechanism, then the caveat. The 'TODO Lane A' internal scaffolding reference is noise for an agent but small.

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 mutation tool with no output schema, the description covers purpose, mechanism, and the unsealed-upload risk. It omits return/idempotency information and any sibling disambiguation, which keeps it short of 5.

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 86%, so the schema already documents every parameter (~15 MB decoded max, mime examples, thread_label semantics). The description only echoes 'pass audio bytes as base64', adding nothing beyond the schema — baseline 3 is correct.

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+resource ('Send a VOICE note ... as a first-class mDM `voice` message, not a URL stub') and clarifies the mechanism (base64 upload to Storage, posted via message-send). It never distinguishes itself from the ambiguous sibling `mDM_voice_note`, so an agent cannot fully route between them from this text alone.

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 when-to-use / when-not guidance and no alternatives are named, despite the existence of `mDM_voice_note`, `mDM_send_file`, and `mDM_send_unencrypted` as obviously relevant siblings. The SCAFFOLD note is a caveat, not usage guidance.

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