Agent402.Tools: pay-per-call web tools

Speech-to-text

audio.transcribe

Paid ($0.030/call): Transcribe audio to text with the gpt-transcribe model. Provide a URL to an audio file (mp3, wav, m4a, etc.) and get back the transcript. Add diarize:true for speaker labels, word timestamps and a language confidence score (the scribe-v2 model, same price). No API key needed; pay per call via x402.

Input Schema

Name	Required	Description
`url`	Yes	URL of the audio file to transcribe (mp3, wav, m4a, ogg, flac, webm)
`diarize`	No	true: transcribe with the scribe-v2 model and add speaker labels and word timestamps (`words`, `speakers`) and `language_confidence` (0 to 1, the model's confidence in the detected language). Same price and cap. Default false
`language`	No	Optional ISO-639-1 language code (e.g. 'en', 'es', 'fr') for better accuracy

Output Schema

Name	Required	Description	Default
`text`	Yes
`model`	No
`duration`	No
`language`	No
`provider`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 15, 2026

changedInput schema / properties / diarize / description

Previous value: -"true: transcribe with the scribe-v2 model and add speaker labels and word timestamps (`words`, `speakers`). Same price and cap. Default false"New value: +"true: transcribe with the scribe-v2 model and add speaker labels and word timestamps (`words`, `speakers`) and `language_confidence` (0 to 1, the model's confidence in the detected language). Same price and cap. Default false"

Changed1 schema field changedOct 11, 2026

changedInput schema / properties / diarize / description

Previous value: -"true: transcribe with ElevenLabs Scribe v2 and add speaker labels and word timestamps (`words`, `speakers`). Same price and cap. Default false"New value: +"true: transcribe with the scribe-v2 model and add speaker labels and word timestamps (`words`, `speakers`). Same price and cap. Default false"

Changed1 schema field changedOct 8, 2026

addedInput schema / properties / diarize

Added value: +{
+  "description": "true: transcribe with ElevenLabs Scribe v2 and add speaker labels and word timestamps (`words`, `speakers`). Same price and cap. Default false",
+  "type": "boolean"
+}

AddedAug 10, 2026

TDQS

A4.4/5.0

Behavior5/5

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

Goes well beyond the annotations: discloses per-call pricing ($0.030), that no API key is needed, that billing happens via x402, that diarize swaps to the scribe-v2 model at the same price and cap, and that output gains extra fields. This is exactly the cost/auth/model-substitution context annotations cannot carry.

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

Conciseness4/5

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

Four tight sentences with the cost and capability front-loaded; every clause carries decision-relevant information. The closing sentence partially restates the opening 'Paid ($0.030/call)' point, a minor redundancy.

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

Completeness5/5

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

Return values are covered by the output schema, and parameter details by a fully-described schema, so the description only needs to supply cost, auth path, and model behavior — all of which it does. Nothing needed to invoke it correctly is missing.

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 coverage is 100%, so the schema already documents all three parameters including the diarize output fields. The description adds a little (same price/cap for diarize) but omits the optional `language` parameter entirely, so it doesn't meaningfully exceed the schema.

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

Purpose5/5

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

States a specific verb and resource ('Transcribe audio to text'), names the underlying model (gpt-transcribe), and specifies the input form (a URL to an audio file). No sibling tool in the list offers transcription, so there is no ambiguity to resolve.

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

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear conditional guidance for the main optional path ('Add diarize:true for speaker labels, word timestamps and a language confidence score') and states the input requirement. It does not spell out when-not-to-use or compare against any alternative, but no plausible alternative exists among the siblings.

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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