Embers: Tabletop RPG Toolkit

Add a rule to a campaign's allowlist

play_add_campaign_rule

Add a vault rule to a campaign's allowlist. The rule always lands on the leg matching the RULE's own ruleset — the campaign must have a leg for that ruleset or play answers 400. The optional ruleset param never retargets; it only confirms the expected leg, and a mismatch answers 400 (e.g. "This rule is X, not Y"). Caller must be the campaign's owner, a gamemaster or player with an accepted seat (watchers excluded), or an admin with Admin Mode on.

Input Schema

Name	Required	Description
`ruleId`	Yes	Vault document id (`ruleId`). Required.
`ruleset`	No	Optional confirmation of the target leg's ruleset. The entity always lands on the leg matching its OWN ruleset — this param never retargets; when present, play verifies it matches that leg and answers 400 on a mismatch. Omit unless you want the placement double-checked.
`campaignId`	Yes	Campaign id.

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 27, 2026

removedInput schema / properties / ruleset / enum

Removed value: -[
-  "5th Edition",
-  "5e24",
-  "PFRPG",
-  "PFRPG2",
-  "PF Playtest",
-  "Savage Worlds",
-  "Savage Embers",
-  "Solarian Conflict",
-  "Embers RPG",
-  "Universal",
-  "Fate Core",
-  "Fate Accelerated"
-]

addedInput schema / properties / ruleset / minLength
```
Added value: +1
```

First observedSep 21, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations only declare the generic mutation profile (readOnly=false, idempotent=false, openWorld=true); the description adds substantive behavior beyond that: the rule always lands on the leg matching its own ruleset, the campaign must have that leg, the optional param never retargets, and two distinct 400 conditions with an example message. Authorization is also fully enumerated.

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?

Front-loaded with the action, then behavior, then authorization; every sentence carries distinct information with no filler. It is dense and packs three edge cases into one paragraph, which is justified but leaves little breathing room.

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?

With an output schema present, return values need no explanation, and the description covers the remaining gaps: placement semantics, both error conditions, and the full authorization matrix. Nothing an agent needs to invoke it correctly is missing.

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 100%, so the baseline is 3, but the description adds real meaning: it clarifies that placement is governed by the RULE's own ruleset (not the caller or the campaign) and that `ruleset` is a confirmation-only field with a documented failure mode. This goes slightly beyond the schema's own wording.

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?

States a specific verb and resource ('Add a vault rule to a campaign's allowlist'), which cleanly distinguishes it from play_remove_campaign_rule and the sibling add tools (play_add_campaign_spell/item/character). An agent can identify the operation without opening the schema.

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?

Gives a concrete precondition for use ('the campaign must have a leg for that ruleset or play answers 400') and spells out who may call it. It does not name an alternative tool or a when-not scenario, but the context is clear enough to select it correctly.

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

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