Predictive Maintenance MCP Server

calculate_bearing_characteristic_frequencies

Calculate bearing fault frequencies (BPFO, BPFI, BSF, FTF) from geometry and speed to diagnose rolling-element bearing issues.

Instructions

Calculate bearing characteristic frequencies from geometry.

Standard rolling-element kinematic formulas (Randall & Antoni 2011,
"Rolling element bearing diagnostics — A tutorial", MSSP 25(2)).
Requires the EXACT geometry — from the manual, the catalog
(search_bearing_catalog), or the user; never guessed. Deep-groove
ball bearings have contact_angle_deg = 0.

Args:
    num_balls: Number of rolling elements (Z)
    ball_diameter_mm: Ball/roller diameter (Bd) in mm
    pitch_diameter_mm: Pitch circle diameter (Pd) in mm
    contact_angle_deg: Contact angle (alpha) in degrees
    rpm: Shaft rotation speed in RPM
    ctx: MCP context. Unused — see this module's docstring on logging.

Returns:
    Dictionary with BPFO, BPFI, BSF, FTF in Hz.

Example:
    >>> # 6205 geometry (CWRU Bearing Data Center) at 1797 RPM
    >>> freqs = calculate_bearing_characteristic_frequencies(
    ...     num_balls=9, ball_diameter_mm=7.94,
    ...     pitch_diameter_mm=39.04, rpm=1797
    ... )
    >>> round(freqs['BPFO'], 2)
    107.36

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": {
      "num_balls": "<num_balls>",
      "ball_diameter_mm": "<ball_diameter_mm>",
      "pitch_diameter_mm": "<pitch_diameter_mm>"
    },
    "name": "calculate_bearing_characteristic_frequencies"
  }
}

Input Schema

Name	Required	Description	Default
`rpm`	No
`num_balls`	Yes
`ball_diameter_mm`	Yes
`contact_angle_deg`	No
`pitch_diameter_mm`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv0.9.1Jul 15, 2026

addedInput schema / properties / rpm

Added value: +{
+  "default": 1500,
+  "title": "Rpm",
+  "type": "number"
+}

removedInput schema / properties / shaft_speed_rpm

Removed value: -{
-  "default": 1500,
-  "title": "Shaft Speed Rpm",
-  "type": "number"
-}

First observedv0.8.0May 26, 2026

TDQS

A4.5/5.0

Behavior4/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It transparently specifies the exactness requirement ('never guessed'), identifies the formula source, states that ctx is unused, and lists the return dictionary. This is solid but not exhaustive; it omits error conditions or edge cases.

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?

The description is well-structured and front-loaded with the purpose. Each section—usage note, args, returns, example—earns its place. The example is relevant and compact, showing a typical call and output. No redundancy; length is appropriate for the tool's complexity.

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?

Given the presence of an output schema, the description need not elaborate on return values, but it still notes they are in Hz. It covers input sourcing, formula reference, defaults, and includes a worked example. Missing are the physical meanings of each characteristic frequency and any valid range or error handling, but for a calculation tool this is adequate.

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 description coverage is 0%, so the description fully compensates by providing symbols, meanings, and units for every parameter (e.g., 'num_balls: Number of rolling elements (Z)'). It also clarifies the default for contact_angle_deg and notes ctx is unused. This is exemplary parameter documentation.

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 opens with a specific verb and resource: 'Calculate bearing characteristic frequencies from geometry.' It names the exact outputs (BPFO, BPFI, BSF, FTF) and cites a standard reference, making its purpose unmistakable and distinct from sibling analysis tools.

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

Usage Guidelines4/5

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

The description clearly states when it should be used: when exact geometry is available from the manual, catalog, or user, and cautions against guessing. It also notes the deep-groove ball bearing contact angle default. However, it does not explicitly mention when not to use it or propose alternatives, so it stops short of a 5.

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