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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, and the description adds valuable context beyond those: the probe follows redirects, sends no payload, requires no API key, is rate-limited, and returns a specific text report structure. No contradiction with annotations exists.

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 efficiently structured: primary action and output type first, sibling routing second, safety/behavioral notes third, and return format last. Every sentence carries functional information with no filler or repetition.

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 one-parameter read-only tool with an output schema, the description covers all essential context: redirect-chain behavior, grading scope, leak detection, rate limiting, auth requirements, and the response format. Nothing an agent needs to select or invoke this tool correctly 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?

Schema description coverage is 100%, so the schema already fully documents the url parameter, including scheme handling and redirect behavior. The description adds no parameter-specific meaning beyond what the schema provides, so the high-coverage baseline 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 uses a specific verb phrase—'Follow a URL's HTTP redirect chain and audit response security headers'—and names the exact resources: CSP, HSTS, X-Frame-Options, COOP, CORP, COEP, Permissions-Policy. It also clarifies the grading output and information-leak detection, making the tool's purpose unmistakable and distinct from siblings.

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?

It explicitly states when to use this tool: 'Use this for HTTP-layer/header posture.' It then names two sibling alternatives and their conditions: 'Use ssl_check instead for certificate or TLS-handshake issues, or security_scan for a full domain report.' This gives clear when/when-not guidance.

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