ros_topic_echo

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

There are no annotations, so the description carries the burden. It reveals meaningful behavioral traits: it returns the latest n messages, uses --noarr to exclude array fields, and restricts n to 1–5. While it does not mention error behavior or side effects, the read-only nature is evident from the verb '读取', and the explicit exclusions add useful context.

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 compact, with just two sentences. The main action and key constraints are front-loaded, and the example topics are useful without extra fluff. Every sentence contributes either to clarity or to parameter understanding.

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 description is complete enough for a command-line echo tool, especially given that an output schema exists to define return values. It covers the purpose, the important flags, the n range, and examples for the required parameter. It stops short of explaining failure modes or prerequisites like needing an active ROS environment, but those are unlikely to be essential given the simplicity and output schema.

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 zero description coverage, so the description must compensate. It does so by explaining the meaning of n ('最新 n 条消息') and its range (1–5). It also gives examples for the 'topic' parameter, clarifying the expected format and usage. However, it does not fully define the topic string boundary conditions, which leaves a small gap.

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 primary action: '读取 ROS 话题最新 n 条消息' (read the latest n messages from a ROS topic). It also specifies the --noarr flag and gives concrete example topics, making the resource and scope unmistakable. It does not explicitly name an alternative sibling, but it is sufficiently distinct from the other tools in the list.

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 offers use-case guidance via example topics ('用于查看 /bridge/Instruct、/agent_run/log 等话题内容') which implies when this tool is appropriate. It does not provide explicit 'when not to use' or direct comparisons to alternatives such as ros_topic_status, so the guidance remains implied rather than fully explicit for an agent.

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