mcp-snap7

by daedalus

Overview Schema Source Related Servers Discussions Admin

Python

Local

eb_write

Write edge inputs to a Siemens PLC by specifying a start byte offset and providing data as a hex string.

Instructions

Write edge inputs to PLC.

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": {
      "start": "<start>",
      "data": "<data>"
    },
    "name": "eb_write"
  }
}

Input Schema

Name	Required	Description	Default
`start`	Yes	Start byte offset
`data`	Yes	Hex string of data to write

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jun 8, 2026

TDQS

B3.2/5.0

Behavior2/5

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

No annotations are provided, and the description only mentions the write operation without detailing any behavioral traits such as permissions, side effects, or reversibility. For a mutation tool, this is insufficient.

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?

The description is extremely concise at 6 words, front-loaded with the key action and resource. While it is efficient, it may be too brief to fully inform the agent without additional context.

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 has an output schema (not shown but referenced) and full parameter coverage. However, the lack of usage guidelines and behavioral transparency leaves gaps for a domain with multiple similar tools.

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%, with clear descriptions for both parameters. The tool description adds no extra meaning beyond the schema, but the schema already provides adequate information. Baseline score of 3 is appropriate.

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?

The description clearly states the verb 'Write', the resource 'edge inputs', and the target 'PLC'. It distinguishes from sibling tools like 'ab_write' and 'db_write' which target different PLC types.

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?

No guidance is provided on when to use this tool versus alternatives. With numerous sibling write tools for different PLC types, the description does not help the agent decide which to select.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.