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CHASE MCP Server

CHASE MCP Server

by chase-cps

ensure

Read-onlyIdempotent

Adds a guarantee formula to an assume-guarantee contract, refining the contract with the new condition.

Instructions

Add a guarantee b to the contract: (b -> A, b & G). The result refines the contract.

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": {
      "contract": "<contract>",
      "formula": "<formula>"
    },
    "name": "ensure"
  }
}

Input Schema

NameRequiredDescriptionDefault
nameNo
formulaYes
contractYes

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. Changed4 schema fields changedv0.4.2
    • changedInput schema / $defs / ContractSpec / properties / inputs / additionalProperties / anyOf
      Previous value: -[
      -  {
      -    "enum": [
      -      "bool",
      -      "real"
      -    ],
      -    "type": "string"
      -  },
      -  {
      -    "maxItems": 2,
      -    "minItems": 2,
      -    "prefixItems": [
      -      {
      -        "type": "integer"
      -      },
      -      {
      -        "type": "integer"
      -      }
      -    ],
      -    "type": "array"
      -  }
      -]New value: +[
      +  {
      +    "enum": [
      +      "bool",
      +      "real"
      +    ],
      +    "type": "string"
      +  },
      +  {
      +    "maxItems": 2,
      +    "minItems": 2,
      +    "prefixItems": [
      +      {
      +        "type": "integer"
      +      },
      +      {
      +        "type": "integer"
      +      }
      +    ],
      +    "type": "array"
      +  },
      +  {
      +    "pattern": "^(signed |unsigned )?word\\[[1-9][0-9]*\\]$",
      +    "type": "string"
      +  }
      +]
    • changedInput schema / $defs / ContractSpec / properties / inputs / description
      Previous value: -"Input variables: \"bool\", [low, high], or \"real\""New value: +"Input variables: \"bool\", [low, high], \"real\", or \"word[n]\" (\"signed word[n]\")"
    • changedInput schema / $defs / ContractSpec / properties / outputs / additionalProperties / anyOf
      Previous value: -[
      -  {
      -    "enum": [
      -      "bool",
      -      "real"
      -    ],
      -    "type": "string"
      -  },
      -  {
      -    "maxItems": 2,
      -    "minItems": 2,
      -    "prefixItems": [
      -      {
      -        "type": "integer"
      -      },
      -      {
      -        "type": "integer"
      -      }
      -    ],
      -    "type": "array"
      -  }
      -]New value: +[
      +  {
      +    "enum": [
      +      "bool",
      +      "real"
      +    ],
      +    "type": "string"
      +  },
      +  {
      +    "maxItems": 2,
      +    "minItems": 2,
      +    "prefixItems": [
      +      {
      +        "type": "integer"
      +      },
      +      {
      +        "type": "integer"
      +      }
      +    ],
      +    "type": "array"
      +  },
      +  {
      +    "pattern": "^(signed |unsigned )?word\\[[1-9][0-9]*\\]$",
      +    "type": "string"
      +  }
      +]
    • changedInput schema / $defs / ContractSpec / properties / outputs / description
      Previous value: -"Output variables: \"bool\", [low, high], or \"real\""New value: +"Output variables: \"bool\", [low, high], \"real\", or \"word[n]\" (\"signed word[n]\")"
  3. First observedv0.3.1

TDQS

C2.9/5.0
Behavior3/5

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

The annotations already declare readOnlyHint=true, openWorldHint=false, and idempotentHint=true, so the basic safety and idempotency profile is covered. The description adds that the result refines the contract, which is useful behavioral context, but it does not clarify whether the input contract is reused or returned, how invalid formulas are handled, or what the refinement guarantees operationally.

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 only two sentences and front-loads the action. However, the parenthetical notation is cryptic and does not earn its place without explanation, which slightly reduces clarity despite the brevity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

This is a complex formal-methods operation with a nested contract schema, no output schema, and only safety annotations. The description states the high-level effect but omits essential context such as formula syntax, contract-field expectations, return behavior, and preconditions, leaving an agent under-equipped to invoke it correctly.

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?

Top-level schema description coverage is 0%: 'name' is completely undocumented, and 'formula' is only obliquely referenced as 'b' in the description. The description implies that 'contract' is the target and 'formula' is the guarantee being added, but it does not explain formula syntax, contract structure, or the role of the optional name parameter.

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 states a specific verb and resource: adding a guarantee to a contract. It does not differentiate this operation from siblings such as assume or conjoin, and the inline notation '(b -> A, b & G)' is unexplained, but the core purpose is still identifiable.

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?

There is no explicit guidance on when to use this tool versus alternatives like assume, conjoin, or imply. The phrase 'The result refines the contract' hints at the effect but does not tell an agent when this operation is appropriate or when another contract-composition tool should be chosen.

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