echo

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It explicitly states 'Read-only, no network, no payment,' which clearly communicates that this tool has no side effects, no external calls, and no cost. This goes beyond basic description and gives the agent confidence in invoking it safely.

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 two sentences with no redundant words. The primary purpose is front-loaded, followed by the usage context and safety profile. Every sentence delivers distinct value: what it does, when to use it, and what side effects to expect.

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 simple one-parameter tool with an output schema, the description fully covers what an agent needs: purpose, usage scenario, and behavioral constraints. It also mentions the relationship to mux_mount, giving operational context. Nothing essential is missing.

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 already provides 100% coverage of the single parameter with a description ('Payload echoed back unchanged. Default ping.') The tool description does not add further parameter-specific meaning beyond confirming the message is echoed. With full schema coverage, a baseline score of 3 is appropriate.

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 states a specific verb and resource: 'Return the message plus the Proto-OS name to confirm the MCP session is alive.' This clearly defines what the tool does and its purpose. It also distinguishes itself from siblings by framing it as a liveness probe, which is distinct from listing or mounting operations.

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 explicitly states when to use it: 'Use as a liveness probe before mux_mount.' This provides clear context for selecting this tool. It does not mention exclusions or alternatives, but the guidance is specific enough for an agent to know it is the appropriate pre-flight check.

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