Fetch a URL and return clean markdown plus structured JSON (title, author, links, tables). Cost: 2 credits ($0.002).
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": "read_url"
}
}| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | ||
| format | No |
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 adds real behavioral context by disclosing the return shape and the cost (2 credits / $0.002), which is valuable for planning. However, it says nothing about auth requirements, rate limits, redirects, JS-rendered or paywalled pages, or failure 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?
One dense sentence that front-loads the action and return value, then appends the cost. Every clause earns its place; nothing is repeated from the name.
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?
There is no output schema and no annotations, so the description's return-shape detail is genuinely helpful. But for a 2-param tool with 0% schema coverage it leaves the format parameter, error modes, and access constraints unexplained, so it is only partially complete.
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 0% for 2 parameters, so the description must compensate and largely doesn't. It never explains the format enum, and its phrasing implies both markdown and JSON are always returned, which is at odds with a format switch that selects one. The url parameter's expected form (fully qualified URI, http/https) is also unaddressed.
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 (fetch) and resource (URL) and describes the payload returned (clean markdown plus structured JSON with title, author, links, tables). It does not differentiate itself from the sibling convert_file, so it stops short of a 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?
Usage is only implied: an agent can infer you call this when you need the contents of a web page. There is no statement of when to prefer it over convert_file, no preconditions, and no exclusions. The credit-cost note gives useful context but is not selection guidance.
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.