ROS MCP Server

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

With no annotations provided, the description carries full burden but only states basic behavior. It doesn't disclose critical traits: whether subscription is blocking/non-blocking, error handling for invalid topics/msg_types, message format returned, or if it requires active publishers. The example shows defaults but no behavioral context like rate limits or permissions needed.

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?

Extremely concise with two sentences: a clear purpose statement followed by a comprehensive example showing all parameters. Zero wasted words, front-loaded with the core functionality. The example efficiently demonstrates usage without verbose explanations.

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?

For a 4-parameter tool with no annotations and no output schema, the description is incomplete. It doesn't explain what the tool returns (message format, structure, or error cases), behavioral details like subscription mechanics, or integration with sibling tools. The example helps but doesn't cover output or edge cases, leaving significant gaps for agent understanding.

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 0%, so the description must compensate. The example lists all 4 parameters with sample values, adding meaning beyond schema titles. However, it doesn't explain parameter relationships (e.g., duration vs. max_messages interaction), units for duration, or valid msg_type formats. Baseline would be lower without the example, but it partially compensates.

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 verb 'subscribe' and resource 'topic', specifying the action of collecting messages for a duration. It distinguishes from sibling 'subscribe_once' by emphasizing duration-based collection rather than single-message subscription. However, it doesn't explicitly contrast with other siblings like 'get_topics' or 'get_subscribers_for_topic'.

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 implies usage for collecting multiple messages over time through the example, suggesting when to use this vs. 'subscribe_once' for single messages. However, it lacks explicit guidance on when NOT to use it or alternatives like polling with 'get_message_details'. No prerequisites or context about topic availability are mentioned.

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