hostid

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

Description adds 'Read-only, no side effects' and 'Returns JSON with the host ID' beyond the readOnlyHint annotation. No contradictory information. Could mention auth requirements or rate limits, but not needed for a simple read-only tool.

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?

Four sentences, each serving a distinct purpose: purpose, behavior, use case, and exclusions. Front-loaded with core functionality. No redundant or irrelevant content.

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 read-only tool with one optional parameter and no output schema, the description covers purpose, usage, behavior, return value, and distinctions from related tools. Completely sufficient.

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 covers 100% of parameter descriptions (the 'raw' boolean). Description does not add any additional meaning beyond what the schema already provides, so 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?

Description clearly states 'Return a deterministic host identifier in hexadecimal format'. It distinguishes from siblings by specifying 'Not for the human-readable hostname' and 'Not for full system info', citing alternative tools 'hostname' and 'uname'.

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?

Explicitly says 'Use for stable machine identification' and provides when-not-to-use with clear alternatives: 'Not for the human-readable hostname — use hostname. Not for full system info — use uname.' Also mentions 'See also hostname, uname'.

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