send

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

Annotations already establish a non-destructive, non-idempotent write with no open-world side effects. The description adds one genuinely useful behavioral fact beyond the annotations — that channelId='lobby' is public to everyone — which matters for privacy judgment. It says nothing about rate limits, message persistence, or what happens on failure, so the added value is real but thin.

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 short sentences, front-loaded with the core action and with zero filler. The second sentence is compact to the point of slight ambiguity ('use their own channelId' is terse), but nothing is wasted.

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 two-parameter, no-output-schema tool whose safety profile is fully covered by annotations, the description supplies what the schema cannot: the public visibility of lobby. The main gap is that it never indicates what a successful send returns (message ID, timestamp) or how channelIds are obtained, though neither is strictly required to invoke it.

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%, with both parameters and their bounds (minLength/maxLength) documented in the schema, so the baseline is 3. The description adds only the 'lobby' special-case and the notion that IDs are channel-specific, which the schema does not contain but which is marginal for the text parameter.

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 states a specific verb and resource ("Sends a message to a channel"), which is unambiguous on its own. It does not name or contrast with any sibling (e.g. read, open_dm), so an agent must infer the division of labor from the tool name 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?

Usage is implied rather than stated: mentioning that DMs and server channels use their own channelId hints that another tool (open_dm, list_channels, list_dms) must supply that ID first, but no when-to-use or when-not-to-use guidance is given. There is no explicit alternative named for the DM case, so the agent has to infer the prerequisite chain.

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