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Read ECU snapshot

obd_read_ecu_snapshot

Read-onlyIdempotent

Read an ECU snapshot by providing the vehicle ID and ECU ID to retrieve diagnostic data from a validated, read-only profile.

Instructions

Read an ECU snapshot using only identifiers in a validated, source-labeled read-only profile.

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": {
      "vehicle_id": "<vehicle_id>",
      "ecu_id": "<ecu_id>"
    },
    "name": "obd_read_ecu_snapshot"
  }
}

Input Schema

Name	Required	Description	Default
`ecu_id`	Yes
`vehicle_id`	Yes

Output Schema

Name	Required	Default
`dtcs`	No
`ecu_id`	Yes
`signals`	No
`protocol`	No	unknown
`profile_id`	No
`vehicle_id`	Yes
`captured_at`	No
`profile_source`	No
`profile_confidence`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 28, 2026

TDQS

B3.2/5.0

Behavior3/5

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is clear. The description adds 'validated, source-labeled' context, which is helpful but not critical. No contradictions.

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

Conciseness5/5

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

A single sentence of 13 words that front-loads the verb and resource. No superfluous information. Every word is necessary.

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

Completeness4/5

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

The description is adequate for a simple read-only tool with comprehensive annotations and an output schema (not shown). It could mention what an ECU snapshot contains, but the output schema likely covers that.

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

Parameters2/5

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

The description mentions 'using only identifiers' which loosely maps to the two parameters, but it does not explain what vehicle_id or ecu_id represent or their format beyond the schema. With 0% schema coverage, the description should compensate but fails to do so.

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

Purpose4/5

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

The description clearly states the verb 'Read' and resource 'ECU snapshot', specifying it uses identifiers and is read-only. However, it does not distinguish this from sibling tools like obd_read_standard_pids or obd_read_dtcs, which also read vehicle data.

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?

The description implies this tool is for reading snapshots with valid identifiers in a read-only context, but provides no explicit guidance on when to use it versus alternatives, nor any prerequisites or conditions.

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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