Branchwright MCP

preview_world

Read-onlyIdempotent

Preview deterministic world events based on elapsed time without modifying the save or revealing information to NPCs.

Instructions

Preview deterministic time-driven world events without changing the save or granting NPC knowledge.

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": {
      "campaign_id": "<campaign_id>",
      "branch_id": "<branch_id>",
      "elapsed_minutes": "<elapsed_minutes>"
    },
    "name": "preview_world"
  }
}

Input Schema

Name	Required	Description	Default
`branch_id`	Yes
`campaign_id`	Yes
`destination`	No
`elapsed_minutes`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.0Oct 18, 2026

TDQS

B3.4/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, and the description reinforces this while adding a domain-specific side effect beyond the annotations: no NPC knowledge is granted. That is genuinely new information because 'NPC knowledge' is not covered by any hint. It still doesn't say whether events are returned as a list, how they're ordered, or whether the preview is stable across calls.

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?

A single sentence with no filler, front-loading the action and immediately qualifying the non-mutating scope. Every clause earns its place.

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?

With no output schema and 0% parameter coverage, the description should clarify what a 'preview' actually returns and what the undocumented destination/elapsed_minutes inputs mean. Annotations cover the safety profile, but the agent still cannot predict the response or the effect of the optional parameter.

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% across four parameters, so the description carries the full burden and supplies nothing: campaign_id, branch_id, elapsed_minutes, and especially the optional 'destination' are never explained. An agent gets no help on what destination means (travel destination? branch target?) or how elapsed_minutes bounds relate to the 1440 cap.

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?

States a specific verb (preview) and a well-scoped resource (deterministic time-driven world events), and the qualifier 'without changing the save' implicitly separates it from commit_turn/prepare_turn. It never names a sibling explicitly, so differentiation is left partly to inference.

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?

The phrase 'without changing the save or granting NPC knowledge' implies this is a dry-run/simulation step to use before committing a turn, but no explicit when-to-use or when-not-to-use guidance is given. Alternatives such as commit_turn or prepare_turn are not named.

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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