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

Annotations already establish read-only, non-destructive, idempotent behavior. The description adds an important operational detail—'No browser is launched'—which prevents the agent from assuming Playwright will open a real browser. It does not detail return values or timeout behavior, but the core execution trait is disclosed.

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?

Two short sentences with no filler. The main action is front-loaded, and the key caveat ('No browser is launched') immediately follows. Every word 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?

The tool has 7 heterogeneous parameters and no output schema, yet the description only addresses URLs and provides no context for the unrelated-looking parameters. It also does not explain what 'ok' means (reachable, valid, or something else) or what result the agent should expect.

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 input schema provides individual descriptions for all 7 parameters, so schema coverage is high. The description itself adds no parameter semantics beyond the schema, and it does not explain why parameters like city, json, or ref are relevant to a URL-open check.

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 states a specific action ('Check whether a URL can be opened') and a key differentiator ('No browser is launched'), which helps distinguish it from siblings like browser-url-ok. However, the input schema contains many non-URL parameters (city, json, ref), creating ambiguity about the tool's true scope, so it is not a full 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 phrase 'No browser is launched' implies this is a lightweight alternative to browser-based checking, but the description never explicitly states when to use this tool versus alternatives such as browser-url-ok or web-fetch. Guidance is implied rather than explicit.

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