srdcheck

Overview Schema Source Related Servers Discussions Admin

concentration_check

Calculate the concentration saving-throw DC after damage, and optionally resolve whether concentration holds by including the d20 result and Constitution modifier.

Instructions

Compute the Concentration saving-throw DC when a concentrating creature takes damage: DC = max(10, damage // 2), capped at 30 (SRD 5.2.1 p.179). Optionally pass d20_result (+ con_modifier) to also resolve whether concentration holds. Returns data {dc[, total, success]}. The caller rolls; srdcheck folds.

Input Schema

TableJSON Schema

Name	Required	Description
`damage`	Yes	damage taken while concentrating
`d20_result`	No	optional: the rolled d20 for the Constitution save
`request_id`	No
`con_modifier`	No	Constitution save modifier (used only if d20_result is given)
`table_policy`	No
`asserted_facts`	No
`policy_context`	No
`table_decision`	No

Output Schema

TableJSON Schema

Name	Required	Description	Default
`why`	Yes
`data`	No
`facts`	Yes
`adapter`	Yes
`verdict`	Yes
`rule_ids`	Yes
`citations`	Yes
`exit_code`	Yes
`assumptions`	Yes
`explanation`	Yes
`rule_result`	Yes
`checked_scope`	Yes
`coverage_level`	Yes
`state_mutation`	Yes
`table_decision`	Yes
`unchecked_scope`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.9.0Aug 4, 2026
- addedInput schema / properties / request_id
```
Added value: +{
+  "maxLength": 244,
+  "minLength": 1,
+  "type": "string"
+}
```

Changed15 schema fields changedv0.8.0Aug 3, 2026

addedInput schema / properties / asserted_facts

Added value: +{
+  "items": {
+    "additionalProperties": false,
+    "properties": {
+      "confidence": {
+        "maximum": 1,
+        "minimum": 0,
+        "type": "number"
+      },
+      "path": {
+        "pattern": "^/",
+        "type": "string"
+      },
+      "source": {
+        "additionalProperties": false,
+        "properties": {
+          "id": {
+            "maxLength": 256,
+            "minLength": 1,
+            "type": "string"
+          },
+          "kind": {
+            "enum": [
+              "caller",
+              "dm",
+              "player",
+              "agent",
+              "transcript",
+              "sensor",
+              "imported-state",
+              "system"
+            ],
+            "type": "string"
+          }
+        },
+        "required": [
+          "kind"
+        ],
+        "type": "object"
+      }
+    },
+    "required": [
+      "path",
+      "source",
+      "confidence"
+    ],
+    "type": "object"
+  },
+  "type": "array"
+}

addedInput schema / properties / policy_context

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "campaign_id": {
+      "maxLength": 256,
+      "minLength": 1,
+      "type": "string"
+    },
+    "encounter_id": {
+      "maxLength": 256,
+      "minLength": 1,
+      "type": "string"
+    },
+    "request_id": {
+      "maxLength": 256,
+      "minLength": 1,
+      "type": "string"
+    },
+    "session_id": {
+      "maxLength": 256,
+      "minLength": 1,
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

addedInput schema / properties / table_decision

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "kind": {
+      "enum": [
+        "ruling",
+        "override"
+      ],
+      "type": "string"
+    },
+    "lineage": {
+      "additionalProperties": false,
+      "properties": {
+        "affected_query": {
+          "minLength": 1,
+          "type": "string"
+        },
+        "affected_rule_ids": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "authority": {
+          "enum": [
+            "table-ruling"
+          ],
+          "type": "string"
+        },
+        "source_rule_unchanged": {
+          "enum": [
+            true
+          ],
+          "type": "boolean"
+        }
+      },
+      "required": [
+        "authority",
+        "affected_query",
+        "affected_rule_ids",
+        "source_rule_unchanged"
+      ],
+      "type": "object"
+    },
+    "origin": {
+      "additionalProperties": false,
+      "properties": {
+        "id": {
+          "maxLength": 256,
+          "minLength": 1,
+          "type": "string"
+        },
+        "kind": {
+          "enum": [
+            "dm"
+          ],
+          "type": "string"
+        }
+      },
+      "required": [
+        "kind"
+      ],
+      "type": "object"
+    },
+    "outcome": {
+      "maxLength": 1024,
+      "minLength": 1,
+      "type": "string"
+    },
+    "policy_id": {
+      "maxLength": 256,
+      "minLength": 1,
+      "type": "string"
+    },
+    "reason": {
+      "maxLength": 2048,
+      "minLength": 1,
+      "type": "string"
+    },
+    "reversible": {
+      "type": "boolean"
+    },
+    "scope": {
+      "additionalProperties": false,
+      "properties": {
+        "id": {
+          "maxLength": 256,
+          "minLength": 1,
+          "type": "string"
+        },
+        "kind": {
+          "enum": [
+            "once",
+            "encounter",
+            "session",
+            "campaign"
+          ],
+          "type": "string"
+        }
+      },
+      "required": [
+        "kind"
+      ],
+      "type": "object"
+    },
+    "visibility": {
+      "enum": [
+        "dm-only",
+        "table"
+      ],
+      "type": "string"
+    }
+  },
+  "required": [
+    "kind",
+    "outcome",
+    "origin",
+    "scope"
+  ],
+  "type": "object"
+}

addedInput schema / properties / table_policy

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "policies": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "author": {
+            "additionalProperties": false,
+            "properties": {
+              "id": {
+                "maxLength": 256,
+                "minLength": 1,
+                "type": "string"
+              },
+              "kind": {
+                "enum": [
+                  "dm"
+                ],
+                "type": "string"
+              }
+            },
+            "required": [
+              "kind"
+            ],
+            "type": "object"
+          },
+          "decision": {
+            "additionalProperties": false,
+            "properties": {
+              "kind": {
+                "enum": [
+                  "ruling",
+                  "override"
+                ],
+                "type": "string"
+              },
+              "outcome": {
+                "maxLength": 1024,
+                "minLength": 1,
+                "type": "string"
+              }
+            },
+            "required": [
+              "kind",
+              "outcome"
+            ],
+            "type": "object"
+          },
+          "enabled": {
+            "type": "boolean"
+          },
+          "id": {
+            "maxLength": 256,
+            "minLength": 1,
+            "type": "string"
+          },
+          "query": {
+            "additionalProperties": false,
+            "properties": {
+              "match": {
+                "additionalProperties": {},
+                "type": "object"
+              },
+              "type": {
+                "maxLength": 256,
+                "minLength": 1,
+                "type": "string"
+              }
+            },
+            "required": [
+              "type",
+              "match"
+            ],
+            "type": "object"
+          },
+          "reason": {
+            "maxLength": 2048,
+            "minLength": 1,
+            "type": "string"
+          },
+          "reversible": {
+            "type": "boolean"
+          },
+          "scope": {
+            "additionalProperties": false,
+            "properties": {
+              "id": {
+                "maxLength": 256,
+                "minLength": 1,
+                "type": "string"
+              },
+              "kind": {
+                "enum": [
+                  "once",
+                  "encounter",
+                  "session",
+                  "campaign"
+                ],
+                "type": "string"
+              }
+            },
+            "required": [
+              "kind",
+              "id"
+            ],
+            "type": "object"
+          },
+          "visibility": {
+            "enum": [
+              "dm-only",
+              "table"
+            ],
+            "type": "string"
+          }
+        },
+        "required": [
+          "id",
+          "author",
+          "reason",
+          "query",
+          "decision",
+          "scope",
+          "visibility",
+          "reversible"
+        ],
+        "type": "object"
+      },
+      "maxItems": 1000,
+      "type": "array"
+    },
+    "schema": {
+      "enum": [
+        "srdcheck.table-policy/1.0"
+      ],
+      "type": "string"
+    },
+    "table": {
+      "maxLength": 256,
+      "minLength": 1,
+      "type": "string"
+    }
+  },
+  "required": [
+    "schema",
+    "policies"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / assumptions

Added value: +{
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / checked_scope

Added value: +{
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / coverage_level

Added value: +{
+  "enum": [
+    "unknown",
+    "registry-only",
+    "budget-only",
+    "rule-surface-complete",
+    "full-context-checkable"
+  ],
+  "type": "string"
+}

addedOutput schema / properties / explanation

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "rule": {
+      "type": "string"
+    },
+    "situation_facts": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "state_mutation": {
+      "type": "string"
+    },
+    "table_decision": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "rule",
+    "situation_facts",
+    "table_decision",
+    "state_mutation"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / facts

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "asserted": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "confidence": {
+            "maximum": 1,
+            "minimum": 0,
+            "type": [
+              "number",
+              "null"
+            ]
+          },
+          "path": {
+            "type": "string"
+          },
+          "source": {
+            "additionalProperties": false,
+            "properties": {
+              "id": {
+                "maxLength": 256,
+                "minLength": 1,
+                "type": "string"
+              },
+              "kind": {
+                "enum": [
+                  "caller",
+                  "dm",
+                  "player",
+                  "agent",
+                  "transcript",
+                  "sensor",
+                  "imported-state",
+                  "system"
+                ],
+                "type": "string"
+              }
+            },
+            "required": [
+              "kind"
+            ],
+            "type": "object"
+          },
+          "value": {}
+        },
+        "required": [
+          "path",
+          "value",
+          "source",
+          "confidence"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "consumed": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "derived": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "basis": {
+            "enum": [
+              "rule_result"
+            ],
+            "type": "string"
+          },
+          "path": {
+            "type": "string"
+          },
+          "value": {}
+        },
+        "required": [
+          "path",
+          "value",
+          "basis"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "missing": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "path": {
+            "minLength": 1,
+            "type": "string"
+          }
+        },
+        "required": [
+          "path"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "asserted",
+    "consumed",
+    "derived",
+    "missing"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / rule_result

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "adapter": {
+      "type": "string"
+    },
+    "authority": {
+      "enum": [
+        "rules-advisory"
+      ],
+      "type": "string"
+    },
+    "citations": {
+      "type": "array"
+    },
+    "exit_code": {
+      "type": "integer"
+    },
+    "rule_ids": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "verdict": {
+      "type": "string"
+    },
+    "why": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "authority",
+    "verdict",
+    "exit_code",
+    "why",
+    "adapter",
+    "rule_ids",
+    "citations"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / state_mutation

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "operations": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "op": {
+            "enum": [
+              "replace"
+            ],
+            "type": "string"
+          },
+          "path": {
+            "enum": [
+              "/"
+            ],
+            "type": "string"
+          },
+          "value": {}
+        },
+        "required": [
+          "op",
+          "path",
+          "value"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "status": {
+      "enum": [
+        "none",
+        "proposed"
+      ],
+      "type": "string"
+    }
+  },
+  "required": [
+    "status",
+    "operations"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / table_decision

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "kind": {
+      "enum": [
+        "ruling",
+        "override"
+      ],
+      "type": "string"
+    },
+    "lineage": {
+      "additionalProperties": false,
+      "properties": {
+        "affected_query": {
+          "minLength": 1,
+          "type": "string"
+        },
+        "affected_rule_ids": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "authority": {
+          "enum": [
+            "table-ruling"
+          ],
+          "type": "string"
+        },
+        "source_rule_unchanged": {
+          "enum": [
+            true
+          ],
+          "type": "boolean"
+        }
+      },
+      "required": [
+        "authority",
+        "affected_query",
+        "affected_rule_ids",
+        "source_rule_unchanged"
+      ],
+      "type": "object"
+    },
+    "origin": {
+      "additionalProperties": false,
+      "properties": {
+        "id": {
+          "maxLength": 256,
+          "minLength": 1,
+          "type": "string"
+        },
+        "kind": {
+          "enum": [
+            "dm"
+          ],
+          "type": "string"
+        }
+      },
+      "required": [
+        "kind"
+      ],
+      "type": "object"
+    },
+    "outcome": {
+      "maxLength": 1024,
+      "minLength": 1,
+      "type": "string"
+    },
+    "policy_id": {
+      "maxLength": 256,
+      "minLength": 1,
+      "type": "string"
+    },
+    "reason": {
+      "maxLength": 2048,
+      "minLength": 1,
+      "type": "string"
+    },
+    "reversible": {
+      "type": "boolean"
+    },
+    "scope": {
+      "additionalProperties": false,
+      "properties": {
+        "id": {
+          "maxLength": 256,
+          "minLength": 1,
+          "type": "string"
+        },
+        "kind": {
+          "enum": [
+            "once",
+            "encounter",
+            "session",
+            "campaign"
+          ],
+          "type": "string"
+        }
+      },
+      "required": [
+        "kind"
+      ],
+      "type": "object"
+    },
+    "visibility": {
+      "enum": [
+        "dm-only",
+        "table"
+      ],
+      "type": "string"
+    }
+  },
+  "required": [
+    "kind",
+    "outcome",
+    "origin",
+    "scope"
+  ],
+  "type": [
+    "object",
+    "null"
+  ]
+}

addedOutput schema / properties / unchecked_scope

Added value: +{
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

changedOutput schema / required

Previous value: -[
-  "verdict",
-  "exit_code",
-  "why",
-  "citations",
-  "rule_ids",
-  "adapter"
-]New value: +[
+  "verdict",
+  "exit_code",
+  "why",
+  "citations",
+  "rule_ids",
+  "adapter",
+  "coverage_level",
+  "checked_scope",
+  "unchecked_scope",
+  "assumptions",
+  "facts",
+  "rule_result",
+  "table_decision",
+  "state_mutation",
+  "explanation"
+]

changedOutput schema / x-srdcheck-schema-version
```
Previous value: -"1.0"New value: +"4.0"
```

Changed2 schema fields changedv0.5.1Aug 1, 2026

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": false,
+  "properties": {
+    "adapter": {
+      "type": "string"
+    },
+    "citations": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "page": {
+            "type": "integer"
+          },
+          "quote": {
+            "type": "string"
+          },
+          "section": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "section"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "data": {
+      "type": "object"
+    },
+    "exit_code": {
+      "enum": [
+        0,
+        1,
+        2
+      ],
+      "type": "integer"
+    },
+    "rule_ids": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "verdict": {
+      "enum": [
+        "legal",
+        "illegal",
+        "cannot-adjudicate"
+      ],
+      "type": "string"
+    },
+    "why": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "verdict",
+    "exit_code",
+    "why",
+    "citations",
+    "rule_ids",
+    "adapter"
+  ],
+  "type": "object",
+  "x-srdcheck-schema-version": "1.0"
+}

Addedv0.1.6Jul 26, 2026

TDQS

A4.7/5.0

Behavior5/5

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

With no annotations, the description fully explains behavior: deterministic DC formula, optional d20 check, return shape, and the caller-rolls convention. No side effects or hidden behaviors are involved for this pure computation tool.

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, front-loads the formula, then states optional behavior and return values. Every sentence adds value with no redundancy.

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?

Despite the large schema, the description covers the essential domain logic and return shape. The output schema exists, and the tool is a focused calculation, so the description is complete enough for an agent to select and invoke it correctly.

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 coverage is low (38%), so the description compensates by explaining the key parameters: damage, d20_result, and con_modifier, including their optional relationship. It does not explain infrastructure params like table_policy or asserted_facts, but those are secondary to the tool's core purpose.

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 uses a specific verb ('Compute'), identifies the resource ('Concentration saving-throw DC'), and includes the exact formula and cap. It also distinguishes itself from sibling check-related tools by noting the caller rolls and 'srdcheck folds.'

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 to use the tool ('when a concentrating creature takes damage') and explains the optional d20 resolution path. It lacks explicit named alternatives, but the context and division of responsibility are clear enough.

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