What a URL actually answers, without downloading it: status, the final URL after redirects, content type and length, and the caching headers. No body is read and none is returned. Cheaper and safer than fetching a page to find out whether it is there and what it is.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | An http or https URL. |
Changes observed during successful MCP inspections. Dates show when Glama detected each change.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden. It discloses that no body is read or returned, that redirects are followed (final URL), and that it is cheaper and safer. This covers the core behavioral traits an agent needs, though it could mention error behavior or timeouts. Given the tool's simplicity, this is sufficient.
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 sentences with no filler. The primary output is front-loaded, and the safety note 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?
For a single-parameter tool with no output schema and no annotations, the description explains what is returned (status, final URL, content type, length, caching headers) and that no body is returned. It is complete enough for an agent to call correctly, though it doesn't cover error scenarios explicitly. Minor gap only.
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%, with the only parameter 'url' described as 'An http or https URL.' The description adds no additional meaning beyond the schema, so baseline 3 is appropriate.
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 verb ('answers' a URL) and resource, and enumerates exactly what is returned: status, final URL after redirects, content type and length, caching headers. It clearly distinguishes the tool from a full fetch, and 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?
The description gives a clear usage context: use this to check a URL's existence and metadata without downloading it, stating it is 'cheaper and safer than fetching a page'. It doesn't name specific sibling tools but implies the alternative of a full fetch, providing adequate guidance for when to choose this tool.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.