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

Annotations already declare readOnlyHint=true and idempotentHint=true. The description supplements this with valuable behavioral details: 'Detects multi-value headers, masks Authorization values, and optionally audits for missing security headers.' This adds context about data handling without contradicting the annotation.

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?

Two sentences, front-loaded with the main verb action, and every clause adds substantive information. No wasted words or redundancy with schema.

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?

Given the tool's low complexity, comprehensive annotations, and presence of an output schema, the description covers purpose, key behaviors, and optional features. It does not need to describe return values because the output schema exists. The description is fully adequate for an agent to select and use the tool.

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%, so baseline is 3. The description enriches the 'headers' parameter by explaining multi-value detection and Authorization masking, and adds security header examples (HSTS, CSP, X-Frame-Options) that clarify the 'analyze_security' parameter. This goes beyond the schema's static descriptions.

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 'Parse a raw HTTP headers block into a structured JSON object,' which is a specific verb+resource+output. It distinguishes itself from siblings like parse_csv and security_headers_check by mentioning multi-value detection, Authorization masking, and optional security auditing.

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 implies the use case: when you have a raw HTTP headers block and want structured JSON. It clearly notes the optional security audit feature, which hints at when to use this vs a dedicated security checker, but does not explicitly name alternatives or exclude cases.

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