read_url

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

With no annotations, the description carries the full burden and does so well: it discloses credit cost, the free-tier quota (100 calls/day), and that PDF URLs are transparently converted. Auth/permission requirements and behavior on non-HTML or failing URLs are not covered, so it falls short of 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 tight sentences totaling one line, with the core action front-loaded and cost last. The inline format="markdown" reference is slightly awkward and the middle sentence is dense, but nothing is wasted.

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?

No output schema exists, and the description compensates by enumerating the JSON fields a caller can expect, plus cost and quota. For a two-parameter tool that is close to complete; only auth requirements and edge-case behavior (paywalled/dynamic pages, failures) are 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%, so the 3 baseline applies, but the description goes beyond it by explaining what each format actually yields — "markdown" returns clean markdown while json returns title, author, date, text, links, tables. That connects the enum choice to a concrete outcome.

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 and resource ("Fetch a public URL") and names the return payloads precisely, including auto-conversion of PDF URLs. It is clearly understandable on its own, but it never differentiates itself from the sibling convert_file, so routing between the two remains ambiguous.

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?

Usage is implied by the fetch contract ("public URL"), and the format enum is effectively demonstrated. However there is no explicit when-to-use/when-not guidance and no mention of convert_file as the alternative for non-URL or local-file sources, leaving the agent to infer routing.

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