publish_message

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

No annotations are provided, so the description must fully disclose behavior. It explains that the topic is advertised first, that the action is potentially destructive, that it waits briefly for rosbridge errors, and that failure results in rosbridge_warnings in the response. It also specifies the success return format. This is comprehensive and truthful.

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 succinct and well-structured: a core action sentence, a caution block, then Args and Returns sections. Every sentence serves a purpose. It is front-loaded with the essential information—the action and the safety warning—and no extraneous text.

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 (3 required parameters, nested objects, no schema descriptions, no provided output schema), the description is remarkably complete. It covers the purpose, usage precautions, parameter formats and defaults, behavioral notes (advertisement, error handling), and return values. The AI agent has all necessary information to select and invoke this tool correctly.

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 input schema provides no descriptions for its three parameters. The description compensates fully with detailed Args: topic gets an example path, msg_type gets the required ROS 2 format with examples, and message gets a full JSON example plus the important note that omitted fields default to zero/empty. This adds significant meaning beyond the raw 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 opens with a clear verb+resource: 'Publish a JSON message to a ROS topic (advertises the topic first).' It immediately distinguishes this tool from its siblings, which are primarily read-only (list_topics, get_topic_snapshot, etc.), by emphasizing that it can move a real robot.

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 strong usage guidance: it warns that the tool can move a real robot, recommends reading sensor topics before commanding motion, advises publishing zero velocity to stop, and notes that it is rejected when ROSBRIDGE_MCP_READONLY is set. It could be more explicit about which sibling tools to use instead for reading (e.g., get_topic_snapshot), but the intent is clear.

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