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CHASE MCP Server

CHASE MCP Server

by chase-cps

visualize

Idempotent

Draw assume-guarantee contracts as an interactive web page, composing parts by ports and checking assumptions, guarantees, refinements, and environments to expose specification issues.

Instructions

Draw contracts as a web page: the contracts given as JSON, or the contracts of a specification in the logics language of CHASE (text, or the path of a file). Without draw and refines, the contracts are put together by their ports: an output and an input of the same name are wired; contracts with the same ports are versions of one part, and the first one is wired; a contract whose outputs several parts drive, and which gives them what they read from outside, has the parts drawn inside it. draw names the contracts to draw instead; NAME+NAME draws their composition, a box with the contracts inside, wired by the names of their variables. refines lists [refined, abstract] pairs: the refined one is drawn inside the abstract one, and checked against it. A decomposition is drawn and checked only when a pair names it: refines: [["Sensor+Controller", "Cruise"]]. An input of a part that no other part or input of the box drives is marked (its name in orange). environments lists [model file, contract] pairs: the state machine (SMV, JSON, or a controller of slugs) is drawn on the left of the contract, as an environment. check (the default) checks that the assumptions and the guarantees of each contract can hold together (A ∧ G, with the core when they cannot), and the refinements and the environments drawn; for a file (path), the results are kept next to it (FILE.results.json), and a check of contracts that have not changed is not run again. verify and realizable check each contract drawn, and mark the terms of a core when a check fails. open names the contracts drawn open (their terms, and the core of a check that fails). The page is written to output (default: a new temporary file) and opens in any browser. Returns its path, and for each box its checks.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "visualize"
  }
}

Input Schema

NameRequiredDescriptionDefault
drawNo
openNo
pathNo
textNo
checkNo
outputNo
verifyNo
refinesNo
timeoutNo
contractsNo
realizableNo
environmentsNo

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv0.7.0
    • addedInput schema / $defs / ContractSpec / properties / constants
      Added value: +{
      +  "additionalProperties": {
      +    "anyOf": [
      +      {
      +        "type": "integer"
      +      },
      +      {
      +        "type": "number"
      +      }
      +    ]
      +  },
      +  "description": "Named constants: name -> value; the formulas use the names (repair changes them)",
      +  "title": "Constants",
      +  "type": "object"
      +}
  2. Addedv0.5.0

TDQS

A3.9/5.0
Behavior4/5

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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false; the description adds real value on top: the page is written to `output` (default a new temporary file), opened in a browser, results persisted as FILE.results.json, and unchanged contracts are not re-checked. It also states it returns its path plus per-box checks. Only omission is any mention of the `timeout`/cost profile of checks.

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?

Content is mostly substantive rather than filler, and the purpose is front-loaded in the first clause. However it is delivered as one very long run-on paragraph mixing input formats, layout rules, checking semantics, and return values, with no headers or bullets, which makes it hard to scan for the 12 parameters.

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?

For a 12-parameter tool with 0% schema coverage and no output schema, the description covers the input forms, layout algorithm, check/verify/realizable semantics, refinement and environment handling, output location, and the return value ('its path, and for each box its checks'). The unaddressed `timeout` parameter is the only notable gap.

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?

Schema description coverage is 0% at the top level, so the description carries the burden and mostly does: it defines `draw` (including NAME+NAME composition syntax), `refines` as [refined, abstract] pairs with a concrete example, `environments` as [model file, contract] pairs, `open`, `output`, `path`, `text`, `check`, `verify`, `realizable`, and `contracts`. Only `timeout` is left completely unexplained.

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?

Opens with a concrete verb+resource: 'Draw contracts as a web page', and immediately enumerates the accepted input forms (JSON contracts or a CHASE-logics specification via text/path). It is distinguishable from pure-check siblings like `verify` and `refines` because the deliverable (a rendered page) is stated up front. It stops short of explicitly telling the agent how it differs from those siblings.

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?

Each mode is described with the condition that activates it: 'Without `draw` and `refines`, the contracts are put together by their ports', '`draw` names the contracts to draw instead', '`check` (the default) checks...', '`verify` and `realizable` check each contract drawn'. That is clear contextual guidance for choosing among the tool's own modes. There is no guidance on when to call this instead of the standalone `verify`/`refines`/`is_realizable` siblings.

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