Check a URL: HTTP status, redirect chain, response time and headers. Counts toward the 60 fetches an hour.
Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {
"url": "<url>"
},
"name": "check_url"
}
}| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It does disclose a real behavioral trait — the call counts against a 60-fetches-per-hour quota — and lists what comes back, but says nothing about timeout behavior, failure/error results, whether private or non-HTTP URLs are accepted, or auth needs.
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, and the primary capability plus its return surface is front-loaded before the quota caveat.
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 one-parameter tool with no output schema, the description usefully enumerates the return fields and flags the quota cost. Remaining gaps (error/timeout semantics, URL format expectations) are minor but real for a network-facing tool.
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 0% and the single 'url' parameter has no description at all, so the description must compensate. 'Check a URL' only weakly implies an absolute HTTP(S) URL and gives no format, encoding, or validity constraints beyond that.
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?
Names a specific verb ('Check') and resource ('a URL') and enumerates what it returns: HTTP status, redirect chain, response time, headers. That enumeration implicitly separates it from read_url (content retrieval), though the description never names that sibling explicitly.
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?
Usage is only implied by the listed outputs — an agent infers this is for URL health/diagnostic checks rather than content fetching. There is no explicit 'use this instead of read_url when...' routing and no stated preconditions, though the rate-limit sentence does signal the call has a cost.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.