add_header

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

Annotations provide idempotentHint=true and non-destructive. Description adds context that headers are not replaced, which is valuable. No contradiction with annotations. Could mention overwriting behavior explicitly, but fine as is.

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?

Three sentences, front-loaded with action, no waste. Efficiently communicates purpose, use case, and alternative.

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 2-param tool with idempotent annotation and no output schema, the description is nearly complete. Could mention overwrite behavior for existing key, but implied by 'update'. Good enough.

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 100% with clear param descriptions. Description adds use case context but does not significantly enhance param meaning beyond schema. Baseline 3 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?

Clearly states action: 'Add or update a single custom HTTP header without replacing the others.' Distinguishes from siblings like remove_header and set_headers, and provides a concrete example (X-Trace-Id).

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 when to use: 'Useful for one-off headers' and when not: 'To remove, use remove_header.' Does not explicitly mention set_headers for bulk operations, but context implies it.

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