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

With no annotations, the description carries the full burden. It discloses that the body is discarded, which is useful. However, it fails to mention that the tool accepts many unrelated parameters (city, zone, ref, etc.) and discards them, leaving the agent confused about the tool's actual scope. The description is misleading because it implies the tool only handles URLs, while the schema suggests broader shape-checking behavior.

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 with zero wasted words. It front-loads the core purpose and states a key behavioral detail (body discarded). This is an ideal length for a simple tool, though the brevity comes at the cost of completeness.

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 9 parameters, many of which seem unrelated to the description's single focus on URL fetching. The description provides no information about the other parameters, the output format, or the tool's broader capabilities. Given the complexity and lack of an output schema, this description is grossly inadequate for an agent to correctly use the tool in all its intended contexts.

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 parameters have descriptions, but the tool description adds no value in clarifying how they relate to the tool's purpose. It doesn't explicitly state which parameter is the URL, and it doesn't explain why parameters like 'city' or 'zone' exist. The description could help by mapping parameters to the stated behavior, but it doesn't, leaving the agent to guess.

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 fetches a public URL and returns HTTP status and content type, with body discarded. This is a specific verb and resource, and it distinguishes itself from other URL tools by specifying the exact output. However, it doesn't explicitly name sibling tools, so it's not fully differentiated, but the purpose is unambiguous.

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?

No guidance is provided on when to use this tool versus alternatives like browser-url-ok, fetch-status, or normalize-url. The description doesn't mention any exclusions or preferred scenarios. The agent must infer usage from the purpose alone, which is insufficient for a tool with many URL-related siblings.

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