Embers: Tabletop RPG Toolkit

Update a session

play_update_session

Idempotent

Update a session by id. Use this to append session notes, change the date, rename, or tag the session with the Imagine adventure it belongs to (imagineAdventureId — valid ids come from the campaign's imagineAdventures list on play_get_campaign; null untags). Only the fields you supply are sent. Caller must have session 'contribute' permission. REQUIRES baseUpdatedAt: copy updatedAt from a fresh play_get_session read; a stale or fabricated value is rejected with OUT_OF_SYNC and nothing is written.

Input Schema

TableJSON Schema

Name	Required	Description
`id`	Yes	Mongo `_id` of the session to update.
`date`	No	Session date in `dd/mm/yy` format.
`name`	No	Session name / title.
`image`	No
`status`	No
`dateDay`	No
`summary`	No	Short session summary. Max 150 characters.
`dateYear`	No
`dateMonth`	No
`battlemaps`	No
`characters`	No
`description`	No	Session body / notes / recap. Markdown supported.
`baseUpdatedAt`	Yes	REQUIRED proof that you are working from the latest version: copy the `updatedAt` value verbatim from a FRESH read of this exact record (use the matching get tool first). Values from memory, from an earlier conversation, or guessed timestamps are rejected with OUT_OF_SYNC and nothing is written. After a successful update, the response carries the new `updatedAt` — use that for any follow-up write.
`sessionImages`	No
`imagineAdventureId`	No	Imagine adventure this session is part of. Must be one of the ids in the campaign's `imagineAdventures` list (see play_get_campaign); adventures are linked to the campaign with imagine_link_adventure_to_campaign. Pass null to untag the session. Omit to leave unchanged.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed18 schema fields changedSep 25, 2026

addedInput schema / $schema

Added value: +"http://json-schema.org/draft-07/schema#"

addedInput schema / additionalProperties
```
Added value: +{}
```

addedInput schema / properties / baseUpdatedAt

Added value: +{
+  "description": "REQUIRED proof that you are working from the latest version: copy the `updatedAt` value verbatim from a FRESH read of this exact record (use the matching get tool first). Values from memory, from an earlier conversation, or guessed timestamps are rejected with OUT_OF_SYNC and nothing is written. After a successful update, the response carries the new `updatedAt` — use that for any follow-up write.",
+  "minLength": 1,
+  "type": "string"
+}

addedInput schema / properties / battlemaps

Added value: +{
+  "items": {
+    "additionalProperties": {},
+    "properties": {
+      "_id": {
+        "description": "Mongo `_id` reference (24-character hex string).",
+        "minLength": 1,
+        "type": "string"
+      },
+      "visibleToPlayers": {
+        "type": "boolean"
+      }
+    },
+    "type": "object"
+  },
+  "type": "array"
+}

addedInput schema / properties / characters

Added value: +{
+  "items": {
+    "description": "Mongo `_id` reference (24-character hex string).",
+    "minLength": 1,
+    "type": "string"
+  },
+  "type": "array"
+}

addedInput schema / properties / date

Added value: +{
+  "description": "Session date in `dd/mm/yy` format.",
+  "pattern": "^(\\d{1,2})\\/(\\d{1,2})\\/(\\d{2})$",
+  "type": "string"
+}

addedInput schema / properties / dateDay

Added value: +{
+  "maximum": 31,
+  "minimum": 1,
+  "type": "integer"
+}

addedInput schema / properties / dateMonth

Added value: +{
+  "maximum": 12,
+  "minimum": 1,
+  "type": "integer"
+}

addedInput schema / properties / dateYear

Added value: +{
+  "maximum": 9007199254740991,
+  "minimum": -9007199254740991,
+  "type": "integer"
+}

addedInput schema / properties / description

Added value: +{
+  "description": "Session body / notes / recap. Markdown supported.",
+  "type": "string"
+}

addedInput schema / properties / id

Added value: +{
+  "description": "Mongo `_id` of the session to update.",
+  "minLength": 1,
+  "type": "string"
+}

addedInput schema / properties / image
```
Added value: +{
+  "type": "string"
+}
```

addedInput schema / properties / imagineAdventureId

Added value: +{
+  "anyOf": [
+    {
+      "minLength": 1,
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Imagine adventure this session is part of. Must be one of the ids in the campaign's `imagineAdventures` list (see play_get_campaign); adventures are linked to the campaign with imagine_link_adventure_to_campaign. Pass null to untag the session. Omit to leave unchanged."
+}

addedInput schema / properties / name

Added value: +{
+  "description": "Session name / title.",
+  "minLength": 1,
+  "type": "string"
+}

addedInput schema / properties / sessionImages

Added value: +{
+  "items": {
+    "additionalProperties": {},
+    "properties": {
+      "name": {
+        "type": "string"
+      },
+      "url": {
+        "type": "string"
+      },
+      "visibleToPlayers": {
+        "type": "boolean"
+      }
+    },
+    "type": "object"
+  },
+  "type": "array"
+}

addedInput schema / properties / status

Added value: +{
+  "enum": [
+    "pending",
+    "active",
+    "completed",
+    "cancelled"
+  ],
+  "type": "string"
+}

addedInput schema / properties / summary

Added value: +{
+  "description": "Short session summary. Max 150 characters.",
+  "maxLength": 150,
+  "type": "string"
+}

addedInput schema / required

Added value: +[
+  "id",
+  "baseUpdatedAt"
+]

First observedSep 21, 2026

TDQS

A4.4/5.0

Behavior5/5

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

Beyond annotations, it explains optimistic concurrency via baseUpdatedAt, the OUT_OF_SYNC failure mode with nothing written, partial-update behavior, and the required 'contribute' permission. This is exactly the behavioral context an agent needs and goes far beyond the readOnly/destructive/idempotent hints.

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?

Front-loaded with 'Update a session by id'; each sentence carries a distinct operational fact: what can change, partial updates, permission, and concurrency requirement. There is no filler or redundant preamble.

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 complex 15-parameter mutation with an output schema, the description plus schema cover required auth, concurrency, and core fields, and the output schema covers return values. Ambiguity remains around interaction of date vs dateDay/dateMonth/dateYear and optional image/visibility fields, but not enough to impair safe invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is only 47%, so the description must carry extra weight. It adds meaning for baseUpdatedAt and imagineAdventureId and clarifies partial-update behavior, but leaves date parts, image, battlemaps, sessionImages, and status semantics to schema/enum names. It covers the highest-risk parameters but does not fully compensate for the schema gap.

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 precisely that it updates a session by id and enumerates representative uses (append notes, change date, rename, tag with adventure). This distinguishes it from other play_* update tools and from get/create/delete session 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?

'Use this to ...' gives concrete cases, and it explicitly names play_get_session as a required precursor for a fresh baseUpdatedAt. It does not enumerate exclusions such as when to prefer play_update_campaign or page updates, so it misses full when-not guidance.

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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