send_channel_message

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

With no annotations, the description carries the full burden and does well: it discloses that content is plain text with newlines preserved and URLs auto-linked, that Markdown/HTML render literally, and that a mention whose '@<name>' doesn't match 'name' is silently dropped with no error. It doesn't cover permission requirements, rate limits, or rate of delivery, so it falls short of a 5.

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?

Front-loads the core action, then the prerequisites and the sibling exclusion, then parameter detail. Dense but every line serves a purpose; the multi-line formatting is functional rather than padding, though slightly longer than strictly necessary.

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 need not be explained, and the description covers prerequisites, the reply alternative, content rendering semantics, and the mentions contract including the silent-failure mode. Missing only auth/permission and error-handling context for a mutation tool.

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%, yet the description compensates fully: it explains where team_id/channel_id come from, gives the exact mentions JSON shape ([{"user_id","name"} | {"tag_id","name"}]), points to list_team_members/get_user for user_id and list_team_tags for tag_id, and defines the content-side '@DisplayName' contract.

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 message to a Teams channel'), and immediately distinguishes itself from the reply tool. An agent can differentiate it from send_chat_message and reply_to_channel_message without inspecting schemas.

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?

Provides explicit prerequisites ('Use list_teams -> list_channels to get team_id and channel_id') and names the alternative for the reply case ('use reply_to_channel_message instead'). Both when-to-use and when-not-to-use are covered.

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