Weavers / MCP documentation

Prepare an experiment draft

Create a draft tied to exact strategy, source, and dataset revisions.

Creates a draft or proposalprepare_python_experiment_draft

Required permission: weavers.experiment_drafts.write

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Prepare a Python experiment draft using this project's current source and dataset. I will finish the settings in Weavers.

How it works

Creates a saved draft. It does not start compute or change source code.
Read current project metadata first. Supply the exact revision and hashes returned by Weavers, plus a new draft UUID.
Repeating the identical request with the same draftId reuses the draft (created: false). Do not reuse the ID for different content.
assistant_draft_context_changed means the project was archived or a revision/hash changed. Refresh the context before preparing a new request.
Open the returned relative URL on the Weavers website to finish the settings.

Inputs

Field	Required	Type & constraints
strategyId	Required	UUID string
expectedStrategyRevision	Required	integer; greater than 0
draftId	Required	UUID string
sourceRevision	Required	integer; greater than 0
sourceSha256	Required	string; 64 lowercase hexadecimal characters
datasetVersionId	Required	UUID string
datasetSha256	Required	string; 64 lowercase hexadecimal characters
name	Required	string; at least 1 characters; up to 120 characters

View complete input JSON schema

Input schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "strategyId": {
      "type": "string",
      "format": "uuid",
      "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$"
    },
    "expectedStrategyRevision": {
      "type": "integer",
      "exclusiveMinimum": 0,
      "maximum": 9007199254740991
    },
    "draftId": {
      "type": "string",
      "format": "uuid",
      "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$"
    },
    "sourceRevision": {
      "type": "integer",
      "exclusiveMinimum": 0,
      "maximum": 9007199254740991
    },
    "sourceSha256": {
      "type": "string",
      "pattern": "^[a-f0-9]{64}$"
    },
    "datasetVersionId": {
      "type": "string",
      "format": "uuid",
      "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$"
    },
    "datasetSha256": {
      "type": "string",
      "pattern": "^[a-f0-9]{64}$"
    },
    "name": {
      "type": "string",
      "minLength": 1,
      "maxLength": 120
    }
  },
  "required": [
    "strategyId",
    "expectedStrategyRevision",
    "draftId",
    "sourceRevision",
    "sourceSha256",
    "datasetVersionId",
    "datasetSha256",
    "name"
  ],
  "additionalProperties": false
}

What comes back

Field	Description
draftId, strategyId	String UUIDs.
draftRevision	Integer. Saved draft revision.
created	Boolean. False for an identical repeated request.
mode, readyToRun	Always "python" and false.
url	Relative Weavers URL for reviewing the draft.

This table describes the decoded tool result. MCP wraps it in text content and, for object results, structuredContent.

Worked example

Fictional data. Replace identifiers, revisions and hashes with values from your own Weavers workflow.

Request

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "prepare_python_experiment_draft",
    "arguments": {
      "strategyId": "11111111-1111-4111-8111-111111111111",
      "expectedStrategyRevision": 3,
      "draftId": "44444444-4444-4444-8444-444444444444",
      "sourceRevision": 2,
      "sourceSha256": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
      "datasetVersionId": "22222222-2222-4222-8222-222222222222",
      "datasetSha256": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
      "name": "Example experiment"
    }
  }
}

Decoded result

{
  "draftId": "44444444-4444-4444-8444-444444444444",
  "strategyId": "11111111-1111-4111-8111-111111111111",
  "draftRevision": 1,
  "created": true,
  "mode": "python",
  "readyToRun": false,
  "url": "/eureka?strategy=11111111-1111-4111-8111-111111111111&section=build&pythonView=experiments&experimentDraftId=44444444-4444-4444-8444-444444444444"
}

If the request fails

Sign in and grant weavers.experiment_drafts.write before calling this tool.
Use resources you can access and refresh revision information when it changes.
Check result.isError even when HTTP returns 200.

Find the error and next step →