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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly states the tool is read-only, has no parameters, returns a JSON object with a specific structure, and includes the critical constraint that the working directory is the sandbox root and all passed paths must be inside it. It does not describe error behavior or rate limits, but for a simple self-description tool, this is quite transparent.

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 concise and front-loaded with the core purpose. It packs three sentences of high-value content: what the tool returns, the JSON structure, and when to call it. There is no filler or redundant information.

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 tool with no params and no output schema, the description is exceptionally complete. It explains the return format, the critical sandbox-root constraint, and provides a use case. The tool is simple, and the description covers all relevant context without requiring the agent to infer anything.

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 tool has zero parameters, and the schema confirms this with an empty properties object. The description reinforces 'no parameters' and does not need to explain parameter meaning. Baseline for zero-parameter tools is 4, and the description adds value by stating the returned JSON structure, which is more than the schema provides.

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 'Server self-description', which is a specific verb+resource phrase that clearly identifies the tool's purpose. It enumerates exactly what information is returned (version, working directory, languages, tools, limits, contract) and distinguishes it from sibling tools like 'functions' or 'map' by focusing on server metadata rather than code navigation.

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 explicit, actionable usage guidance: 'Call this first if a path is rejected or you need to know what the server can see.' This tells the agent when to invoke the tool and what problem it solves, which is more directive than most descriptions.

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