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

Annotations only declare readOnlyHint=false, so the mutation signal is already covered. The description adds real value beyond that with sub-100ms fan-out, async Supabase flush, idempotency, and the required MOSADD_API_KEY auth, but stops short of error behavior, rate limits, or how a failed flush surfaces. A 3 reflects solid but partial behavioral disclosure.

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?

Purpose and transport are front-loaded ahead of the sibling routing and auth note. The text is dense but every clause (fan-out, flush, idempotency, auth) carries information, with only minor compression gains available.

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 3-param write tool with no output schema, the description covers transport, routing, auth, and delivery semantics. It omits what the call returns (e.g., a message id or ack) and failure modes, which an agent invoking it would want.

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 channel_id, text, and from are already fully documented, including the default for 'from'. The description adds no parameter syntax or constraint details beyond the schema, hitting 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?

States a specific verb (send a text message) and resource (persistent channel), names the transport (mosadd-edge Worker / Durable Object), and explicitly differentiates itself from the mIRC_post_message sibling. An agent can select it 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?

Gives an explicit selection rule: use for native realtime push without polling, and 'Parallel to mIRC_post_message (Supabase path); pick one per channel.' This is exactly the kind of routing guidance that separates near-identical siblings.

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