Nimbus BCI

Protocol.Start Assignment

protocol.start_assignment

Enroll a subject and prepare their neurofeedback deploy session (confirm-gated — a session runs on a human). Creates the assignment (yoked sham arms REQUIRE yoked_donor_upload_id: a recorded simulated session's upload — mint one by running an active-arm session and data.upload-ing its recording), then persists the protocol graph as a deployable execution. Requires a Pro plan for LIVE hardware sessions; simulated-source sessions (the default template) are free.

Graph source: execution_id reuses THAT run's stored graph (it must contain a protocol_session node; no device is pre-connected — the deploy session's data source stays yours). Without execution_id the built-in template graph is cloned — simulated source → bandpass → bandpower_indicator → protocol_session stamped with the protocol refs — and a simulated device is connected to the returned session id.

The session starts when a client opens {statusUrl} (the deploy WS), sends init_deployment with modelExecutionId={executionId}, then start; the Studio app shows the feedback panel automatically. Poll protocol.session_status; stop with protocol.stop (the recording's block annotations + assignment progression are written on stop).

Input Schema

Name	Required	Description
`arm`	Yes	active \| sham.
`confirm`	No	MUST be true — explicit go-ahead for a session on a human.
`protocol_id`	Yes	Saved protocol id (protocol.save).
`execution_id`	No	Optional completed execution whose stored graph carries a protocol_session node; default clones the template.
`subject_label`	Yes	Subject identifier (e.g. "S01").
`protocol_version`	Yes	Immutable version the assignment pins.
`yoked_donor_upload_id`	No	Donor recording upload (required when the arm's blocks resolve to yoked — the backend validates coverage).

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 17, 2026

removedInput schema / properties / name

Removed value: -{
-  "anyOf": [
-    {
-      "type": "string"
-    },
-    {
-      "type": "null"
-    }
-  ],
-  "default": null,
-  "description": "Optional display name for the prepared run."
-}

AddedOct 15, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Annotations already declare readOnlyHint=false, idempotentHint=false, openWorldHint=true; the description goes well beyond them by disclosing the confirm gate, the human-subject risk, plan-gating rules, and what is written on stop (block annotations + assignment progression). It also explains the execution_id graph-reuse vs template-clone branches and the device connection behavior, none of which annotations convey.

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?

Front-loads the core action and the confirm gate before branching into details, and most sentences carry load-bearing information. It is dense and long, with some nested parentheticals that slow reading, costing it a point versus a tighter phrasing.

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?

For a complex, multi-step, human-facing mutation the description covers prerequisites, the graph-source branches, the session startup protocol (open statusUrl, init_deployment, start), and the stop/cleanup path. With an output schema present, return values need not be described, so nothing material is missing.

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

Parameters5/5

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

Schema coverage is 100% (baseline 3), but the description adds real meaning: execution_id reuses that run's stored graph and must contain a protocol_session node (else the template is cloned and a simulated device attached), yoked_donor_upload_id must be minted by running an active-arm session and data.upload-ing its recording, and confirm MUST be true.

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+resource: 'Enroll a subject and prepare their neurofeedback deploy session', then names the two concrete side effects (assignment creation, protocol graph persisted as a deployable execution). This clearly separates it from siblings like protocol.save, protocol.session_status, and protocol.stop.

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

Usage Guidelines5/5

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

Explicitly says when it applies (confirm-gated, session on a human), when NOT to expect free operation (Pro plan required for LIVE hardware; simulated default is free), and routes the lifecycle to alternatives: poll protocol.session_status, stop with protocol.stop. It also states the prerequisite for yoked sham arms and how to mint the donor upload.

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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