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

Goes well beyond the annotations (readOnly/idempotent/openWorld) by disclosing cost ($0.01, no free tier), scope (~40 requests, 443 only, public addresses only, 8 MB), latency (typically 3-10 s, up to 25 s), error semantics (a failing part is reported with its error, not a failed call; private/malformed address = 422 and not charged), and a prompt-injection warning about returned page text and on-chain strings.

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?

Dense but front-loaded: purpose first, then routing to siblings, then return shape, then limits/pricing, ending with a security note. Long, yet each clause (cost, timing, request budget, untrusted-data warning) carries decision-relevant information rather than filler.

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 complex, paid, network-scanning tool it covers cost, timing, request budget, error behavior, auth/access checks, and safety warnings, and an output schema exists so return-value detail is optional. Nothing an agent needs to call it 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 coverage is 100% and the single 'url' param is already fully described in the schema, including the origin-only rule that the description repeats. The description adds no new parameter syntax or format detail beyond what the schema provides, so baseline 3 applies.

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?

States a specific verb+resource ('Check a site's AI-agent readiness') and enumerates the exact dimensions checked (llms.txt, robots, sitemap, schema.org, OpenAPI, MCP). It explicitly distinguishes itself from siblings check_robots_txt, check_mcp_server, and generate_agent_ready_files, so an agent can pick it without opening any schema.

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?

Gives explicit when-to-use alternatives with selecting conditions: 'For one URL's robots rule use check_robots_txt; for a live MCP server probe use check_mcp_server; to fix, generate_agent_ready_files.' Nothing is left to inference about routing.

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