Post a channel message

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

Annotations indicate mutation (readOnlyHint=false) and non-destructiveness. The description adds behavioral details: message creation, max 28000 chars, content type options, and returns a JSON with id and webUrl. It also specifies 'as the signed-in user', clarifying authentication context. Missing details like idempotency or error conditions, but overall good transparency.

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?

The description is short and front-loaded with the main action. The bullet list for args is clear, though it duplicates schema information. Every sentence is useful, but the duplication slightly reduces efficiency. Still well-structured.

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?

Given no output schema, the description includes the return format ({ id, webUrl }). It covers required parameters and constraints. It lacks error handling or rate limit info, but for a straightforward creation tool, it's reasonably complete. Could mention that replies require a different 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?

With 100% schema description coverage, the schema already documents all parameters. The description's Args list largely repeats the schema info (e.g., max chars, default content_type). No additional semantic context beyond the schema, so baseline score of 3 applies.

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 clearly states 'Post a new top-level message to a team channel as the signed-in user.' It uses a specific verb (post) and resource (channel message), and distinguishes from siblings like teams_reply_channel_message (reply) and teams_send_chat_message (chat).

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?

The description does not explicitly state when to use this tool vs alternatives. The term 'top-level' implies it's not for replies, but there is no direct guidance on when not to use it or mention of sibling tools. The parameter descriptions indirectly provide context (e.g., where to get IDs), but the main description lacks clear usage boundaries.

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