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

No annotations are provided, so the description carries the behavioral disclosure burden. It discloses the billing cost ('Billing per call: 1 Credits') and the core behavior of fetching and returning page source. It does not mention potential errors, redirects, authentication requirements, or response format, but for a simple read-style tool this is acceptable though not rich.

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 two short sentences: one for the tool's function and one for billing. Every word earns its place, with no fluff or redundancy. It is appropriately sized for a single-parameter tool.

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?

Given the tool's simplicity—one parameter, no output schema, no nested objects—the description is mostly complete. It states what is fetched and returned, and mentions billing. It could be more complete by describing error behavior or response format, but for this low-complexity tool it is adequate.

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?

The schema has one parameter, 'url', with an example but no description, and schema description coverage is 0%. The description only repeats 'provided url' without adding meaningful detail about URL format, encoding, or constraints. Since the description must compensate for low schema coverage and does not, the score is low.

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 clearly states the tool's function: 'Fetches and returns page source of provided url.' This is a specific verb+resource pairing. However, with no sibling tools listed, it cannot distinguish itself from alternatives, so it does not earn a 5.

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?

The description implies usage: call this tool when you need the page source for a given URL. It does not provide explicit when-to-use vs. when-not-to-use guidance or mention alternatives, but the intended use case is reasonably clear from the wording.

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