FreeDailyPro Calculators

convert_length

Read-onlyIdempotent

Unit converter (length)

Tool call template

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": {
      "value": "<value>",
      "from": "<from>",
      "to": "<to>"
    },
    "name": "convert_length"
  }
}

Input Schema

Name	Required	Description
`to`	Yes	To: one of m, cm, mm, km, in, ft, yd, mi.
`from`	Yes	From: one of m, cm, mm, km, in, ft, yd, mi.
`value`	Yes	The number to convert, for example: 12.5.

Schema Changelog

Changes observed during successful MCP inspections.

Changed5 schema fields changedNov 13, 2026

removedInput schema / $schema

Removed value: -"http://json-schema.org/draft-07/schema#"

removedInput schema / additionalProperties
```
Removed value: -false
```

addedInput schema / properties / from / description

Added value: +"From: one of m, cm, mm, km, in, ft, yd, mi."

addedInput schema / properties / to / description

Added value: +"To: one of m, cm, mm, km, in, ft, yd, mi."

addedInput schema / properties / value / description

Added value: +"The number to convert, for example: 12.5."

First observedOct 24, 2026

TDQS

C2.6/5.0

Behavior2/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds nothing beyond that: no note on rounding/precision, no statement that output is a bare number in the target unit, and no mention of whether invalid or negative values are accepted.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

It is a single short phrase with zero wasted words, so it is maximally concise and front-loaded. However, the brevity crosses into under-specification: it makes no attempt to convey precision, return format, or scope, so conciseness is achieved by omission rather than by careful editing.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool is simple (3 required params, no nesting, no output schema needed for a scalar result), and annotations plus a fully documented schema cover most agent needs. Still, a one-phrase description leaves gaps on precision and return value that would be trivial to close for such a low-complexity tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, with both enumerable parameters documented inline and the enum lists constraining valid units, so the schema carries the parameter burden. The description contributes no additional meaning about the three parameters, which matches the baseline 3 for fully documented schemas.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose3/5

Does the description clearly state what the tool does and how it differs from similar tools?

'Unit converter (length)' names the resource domain (length) and the operation (conversion), which lets an agent distinguish it from convert_weight or convert_temperature. But the phrase is terse and reads close to a restatement of the tool name, with no detail on conversion semantics or precision.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

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 tool, no mention of when not to, and no reference to sibling converters for other measurement domains. An agent must infer entirely from the name and enum values that this handles m/cm/mm/km/in/ft/yd/mi only.

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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