send-message

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

No annotations are provided, so the description must disclose behaviors. It explains that the tool sends messages and gives input validation notes (e.g., 'topic' required for streams), but does not cover idempotency, rate limits, or error scenarios. Adequate but lacks depth.

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?

Three sentences with no wasted words. The purpose is stated first, followed by critical usage tips. Efficient and 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?

The tool has no output schema and moderate complexity. The description covers core functionality, parameter usage, and prerequisites. Could add more about error handling or limitations, but is sufficient for a basic messaging 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 description coverage is 100%, and the description adds significant value: it explains the 'type' enum values, how to format 'to' for streams vs. DMs, gives Markdown examples for 'content', and clarifies the conditional requirement for 'topic'. This goes well beyond the schema.

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 action ('Send a message') and the resources ('Zulip stream' or 'direct message to users'). It distinguishes between the two message types, and the purpose is unique among siblings such as delete-message or edit-message.

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?

Explicit guidance is provided: use exact stream names from 'get-subscribed-streams', use email addresses from 'search-users' for DMs (not display names), and include 'topic' for stream messages. These instructions prevent common errors but do not contrast with sibling tools.

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