send_message

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

With no annotations, the description fully discloses behaviors: messages are tagged with :robot_face: in user-token mode, mentions are auto-resolved, and formatting uses Slack mrkdwn. It does not cover potential side effects or rate limits, but the core behavioral traits are well explained.

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 relatively long but well-structured with clear sections (NOTE, MENTIONS, SLACK URLs, FORMAT). It front-loads the core purpose and then provides necessary details. Every sentence adds value, though some agents might find it slightly verbose.

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 the tool's complexity (4 parameters, 100% schema coverage), the input side is well-covered. However, there is no output schema, and the description does not explain the return value (e.g., message timestamp, error handling). For a complete understanding, the agent might need to infer this from context.

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?

The schema has 100% parameter description coverage, yet the tool description adds significant extra meaning: e.g., 'channel' advises preferring ID and avoiding name guessing, 'thread_ts' details URL extraction, and 'reply_broadcast' explains the checkbox analogy. This greatly aids the agent in correct parameter usage.

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 the tool sends a message to a Slack channel or thread, distinguishing between user-token and bot-token modes. It specifies that it only posts to channels, not DMs, making the purpose unambiguous and distinct from any potential sibling tools.

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 provides explicit guidelines: when to use (sending messages to channels), what not to use (DMs not supported), and how to handle mentions and Slack URL extraction. It also includes formatting instructions, giving the agent clear rules for correct invocation.

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