Distance and travel time between two places.
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": {
"from": "<from>"
},
"name": "distance"
}
}| Name | Required | Description | Default |
|---|---|---|---|
| to | No | Destination place | |
| from | Yes | Origin place |
Changes observed during successful MCP inspections.
Input schema / properties / fromAdded value: +{
+ "description": "Origin place",
+ "type": "string"
+}Input schema / properties / toAdded value: +{
+ "description": "Destination place",
+ "type": "string"
+}Input schema / requiredAdded value: +[
+ "from"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full disclosure burden and largely fails it. It never states the travel mode (driving/walking), distance units, whether a routing/geocoding backend is required, or whether the call can fail on ambiguous place names. Only the basic notion of returning distance plus travel time is conveyed.
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?
A single front-loaded sentence with no wasted words, which is appropriate for a two-parameter tool. Its brevity edges into under-specification, but nothing is redundant or padded.
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 no annotations and no output schema, the description should at minimum say what a result looks like (units, travel mode, structure). Instead it leaves the agent guessing about units, routing mode, and failure behavior on unresolvable places.
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% (both from/to are documented as origin/destination), so the schema does the heavy lifting and baseline 3 applies. The description adds no meaning beyond that, such as whether places are free-text names, addresses, or coordinates, and it does not explain why only "from" is required.
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?
"Distance and travel time between two places" states a specific resource (distance/travel time) and the input shape (two places), so an agent knows exactly what is computed. It does not differentiate itself from nearby siblings like geocode, reverse_geocode, or ie_rail, which also return location-derived information.
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 versus geocode (which can give coordinates) or ie_rail (specific route data). No exclusions, no prerequisites, and no indication of what kind of places (addresses, cities, coordinates) are accepted.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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