Url Access Flags

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

Annotations already provide readOnlyHint, openWorldHint, idempotentHint, destructiveHint. The description adds context about non-execution of JavaScript, no bypass of access controls, and caching behavior, which goes beyond the annotations. No contradiction.

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 four sentences, each serving a purpose: what it does, constraints, how to pass url, and parameter guidance. Front-loaded with the core purpose. No wasted words.

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?

The description covers the tool's purpose, usage constraints, parameter details, and behavior. The output schema exists, so explaining return values is unnecessary. Given the tool's simplicity (2 parameters, no nested objects), the description is fully complete.

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% with detailed descriptions for both parameters. The description adds emphasis on 'public' URLs and provides usage guidance on caching, which adds value beyond the schema. Baseline 3 due to high schema coverage, but the extra guidance justifies a 4.

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 reports 'heuristic authentication, paywall and JavaScript access flags', which is a specific verb and resource. It distinguishes itself from sibling tools like url_status or url_headers by focusing on access flags.

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 explicitly states when to use ('public HTTP(S) resources'), what not to do ('does not execute JavaScript or bypass access controls'), and gives clear guidance on the 'fresh' parameter ('Keep fresh=false to allow cache reuse; set fresh=true only when a new upstream fetch is required').

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