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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is low; the description nonetheless adds the single most decision-relevant trait, that rendering is server-side only and SPA or empty-text pages return nothing useful. It stops short of auth needs, rate limits, redirects, size/truncation caps, or error behavior for non-HTML responses, which is why it is not a 5.

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 plus an example, front-loaded with the purpose before limitations and routing. The sample request URL is slightly noisy for a single-parameter tool, but it does demonstrate the call shape, so it mostly earns its place.

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?

An output schema exists, so return-value documentation is unnecessary, and the description covers purpose, the JS limitation, and alternatives. It is nearly complete; minor gaps remain around non-HTML payloads (notably the sibling pdf_to_markdown) and any truncation or error semantics.

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?

Only one parameter with 100% schema coverage, so the baseline is 3. The description adds one meaningful qualifier the schema lacks — the URL must be public/reachable — but gives no syntax guidance beyond the bare example URL, which the schema already implies.

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 a public URL') plus the exact output form ('clean LLM-ready Markdown from the server-rendered response'). It also carves out the boundary against web_search and pdf_to_markdown by explaining that JS-rendered pages are out of scope, so an agent can route without opening sibling schemas.

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 ('after web_search to read a reachable public source, or to ingest a static page for analysis'), explicit when-not ('does not execute browser JavaScript'), and names concrete alternatives for the failure case (web_search, a browser, or the site's API). Nothing about selection is left to inference.

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