OPC UA MCP Server

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get_server_status

Read-onlyIdempotent

Verify OPC UA connection health and report endpoint, security, server state, build info and namespace index mappings; returns connected:false with a reason instead of failing.

Instructions

Report whether this MCP server is connected to the OPC UA server and what that server says about itself: its endpoint and connection security, its ServerStatus (state, current time, start time, build info) and its NamespaceArray as index -> URI. The one tool that answers while the connection is down — it reports 'connected': false and why, rather than failing — so it is both the health check and the first thing to call when another tool cannot reach the server. The namespace array is also how to tell which 'ns=' index belongs to which namespace URI on this server. 'diagnostics' is the server's own ServerDiagnosticsSummary when it publishes one — session and subscription counts, and how many sessions and requests it has rejected — which is what separates 'the server is slow' from 'the server is refusing us'. OPC UA leaves diagnostics optional, so null there means this server does not say, not zero. 'capabilities' says which optional features — value history, event history, aggregates and their names — the server was found to offer, on which session and when: the answer to why read_opcua_history or read_event_history was refused.

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 5, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Beyond the readOnlyHint/idempotentHint annotations, it discloses the key non-obvious behavior: it does not fail when the connection is down, it returns 'connected': false with a reason. It also warns that null diagnostics means the server does not publish them, not zero. That null-versus-zero distinction is genuinely important, though the description leans on detailed return-field semantics that the output schema already carries.

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

Conciseness3/5

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

Purpose is front-loaded in the first sentence, which is good, but the description runs long for a parameterless status tool and devotes several clauses to output fields the output schema already documents. Those clauses are informative but not all of them earn their space here.

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 zero-parameter read-only diagnostic with an output schema and full annotation coverage, nothing an agent needs is missing. Between the annotations and the output schema the contract is fully covered, and the description fills the remaining gaps around failure behavior and diagnostic semantics.

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

Parameters4/5

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

Zero parameters, so there is nothing to disambiguate; the baseline applies. The description correctly spends no space on arguments and instead explains what the no-argument result means.

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 names the specific verb and resource — report whether the MCP server is connected to the OPC UA server, plus endpoint, security, ServerStatus and NamespaceArray. The second sentence explicitly separates it from the rest of the sibling set: it is the health check and the one tool that answers while the connection is down.

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?

Guidance is explicit and conditional: call it first when another tool cannot reach the server, and consult 'capabilities' when read_opcua_history or read_event_history was refused. It also names the concrete use case of mapping 'ns=' indexes to namespace URIs, which no sibling covers.

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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