pet-tools-mcp

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pet_call

Execute a Commodore PET routine in isolation for unit testing. Set A, X, Y registers, then call and halt at RTS for assertion.

Instructions

JSR one routine in isolation (fake return address on the stack, optional A/X/Y on entry) and stop at its RTS — the unit-test primitive: poke inputs, call, then assert registers/memory. Machine ends STOPPED on success, RUNNING on timeout.

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": {
      "routine": "<routine>"
    },
    "name": "pet_call"
  }
}

Input Schema

Name	Required	Description	Default
`a`	No
`x`	No
`y`	No
`routine`	Yes
`session`	No
`timeout`	No

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.3.0Jul 25, 2026

TDQS

A3.5/5.0

Behavior4/5

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

No annotations are provided, so the description carries the full burden. It discloses key behaviors: fake return address on stack, optional register setup, and machine states (STOPPED on success, RUNNING on timeout). This is more transparent than many tool descriptions.

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 two sentences and front-loads the core action and purpose. Every word is useful, with no redundancy. The structure is efficient for quick parsing.

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?

Given the 6 parameters and no output schema, the description covers the main intent and mechanism but omits details about the 'routine' parameter format, 'session' usage, and potential return values. The outcome states are helpful, but additional context would improve completeness.

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?

Schema description coverage is 0%, so the description must compensate. It mentions 'optional A/X/Y on entry' and 'routine', but does not detail the 'session' parameter or the expected format for 'routine' (e.g., address or label). The timeout default is mentioned in the schema but not in the description. This adds limited value beyond parameter names.

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 it performs a JSR to a routine and stops at RTS, describing it as a unit-test primitive. This distinguishes it from generic run/continue tools, though it could explicitly name sibling tools for differentiation.

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

Usage Guidelines3/5

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

It outlines a usage pattern ('poke inputs, call, then assert registers/memory') and describes success/timeout outcomes. However, it does not explicitly state when to use this tool versus alternatives like pet_step or pet_run, leaving implicit guidance.

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