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

Annotations cover the safety profile (readOnly, idempotent, openWorld, non-destructive), and the description adds substantial context beyond them: cost model ($0.005 USDC per call via x402 on Base, errors free), fetch limits (2 MB HTML, 10 s timeout), address restrictions, and exactly what is stripped/rewritten (scripts/nav/footer removed, links made absolute).

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?

A single dense paragraph where every clause carries information: pricing, action, output format, limits, and the optional parameter. The pricing note leads, which is defensible for a paid tool, though it delays the core purpose by one clause.

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?

With no output schema, the description must describe returns, and it does: main content as Markdown with absolute links, plus title and length. Combined with fetch limits, cost, and parameter defaults, an agent has everything needed to call and interpret this 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 both parameters are already documented in the schema, and the description's maxChars detail (default 50000, max 200000) largely restates it. The non-parameter limits it mentions (2 MB HTML, 10 s timeout) add behavioral rather than parameter meaning, so the baseline 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?

States a specific verb+resource: 'Fetch one public web page and return its main content ... as clean Markdown with absolute links, plus title and length.' The output shape (main content extraction vs. raw HTML vs. metadata) implicitly distinguishes it from siblings like page_metadata and screenshot_url, but no sibling is named explicitly.

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 real constraints on when it applies (one public page, hostname not IP, private/reserved addresses refused, 2 MB / 10 s limits), which implies the use case. However, it never states when to prefer this over page_metadata, website_audit, or summarize, nor any exclusions.

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