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

With no annotations, the description must carry the full behavioral disclosure. It states 'No browser is launched,' which is a useful trait, but it does not explain what happens for the many parameters (e.g., whether they are validated, what errors occur, whether any network access is made). The schema notes some parameters are 'discarded,' but that is in the schema, not the description. The description lacks detail on side effects, return values, or failure modes.

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 extremely concise (two short sentences), but the brevity is not effective because it omits critical information. The first sentence states the purpose, but the second is a behavior note. It lacks any structure to help the agent understand the tool's multi-parameter nature, and it does not front-load the most relevant details for the agent's decision-making.

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?

For a tool with 9 parameters, no required parameters, and no output schema, the description is grossly incomplete. It does not explain the return format, how different parameters are processed, or what success/failure looks like. The tool appears to be a multi-purpose shape checker, but the description only mentions URLs, leaving agents unable to predict behavior for other inputs. This is inadequate for safe and correct invocation.

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 description coverage is 100%, so the schema documents all parameters adequately (e.g., 'Git ref name; discarded after the shape check'). The description adds nothing beyond the schema; it does not synthesize how parameters relate or which are primary. Baseline 3 is appropriate since the schema does the heavy lifting, but the description provides no extra value.

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 says 'Check whether a URL can be opened' but the input schema includes many non-URL parameters (city, json, path, zone, query), suggesting the tool actually checks a variety of shapes. This misalignment makes the purpose unclear and potentially misleading for non-URL inputs. The phrase 'No browser is launched' adds a behavioral note but doesn't clarify the overall scope.

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?

There is no guidance on when to use this tool versus the 26 sibling tools, many of which overlap (e.g., browser-url-ok, fetch-status, normalize-url, validate-json). The description does not mention any alternatives, exclusions, or conditions for selection, leaving the agent without direction.

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