champion_masteryReturn full champion mastery list for a puuid on a platform: mastery level, points, chest granted, tokens earned for every champion.
| Name | Required | Description | Default |
|---|---|---|---|
| puuid | Yes | ||
| platform | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| count | Yes | Number of items returned. | |
| items | Yes | Array of champion mastery entries |
Changes observed during successful MCP inspections.
Input schema / examplesAdded value: +[
+ {
+ "platform": "na1",
+ "puuid": "player-puuid-123456"
+ }
+]Output schema / (root)Previous value: -nullNew value: +{
+ "properties": {
+ "count": {
+ "description": "Number of items returned.",
+ "type": "integer"
+ },
+ "items": {
+ "description": "Array of champion mastery entries",
+ "items": {
+ "properties": {
+ "championId": {
+ "description": "Champion ID",
+ "type": "number"
+ },
+ "championLevel": {
+ "description": "Mastery level",
+ "type": "number"
+ },
+ "championPoints": {
+ "description": "Mastery points",
+ "type": "number"
+ },
+ "championPointsSinceLastLevel": {
+ "description": "Points since last level",
+ "type": "number"
+ },
+ "championPointsUntilNextLevel": {
+ "description": "Points until next level",
+ "type": "number"
+ },
+ "lastPlayTime": {
+ "description": "Last play time timestamp",
+ "type": "number"
+ }
+ },
+ "type": "object"
+ },
+ "type": "array"
+ }
+ },
+ "required": [
+ "items",
+ "count"
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate the tool is read-only, open world, and idempotent. The description adds behavioral context by listing the specific data fields returned (mastery level, points, chest granted, tokens earned), which is beyond what annotations provide. No contradictions.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single concise sentence that front-loads the main action and key details. Every part is essential, with no wasted words.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool is simple with 2 parameters, and an output schema exists to define return values. The description covers the main purpose and data fields. It does not mention pagination, ordering, or rate limits, but given the annotations and simplicity, it is sufficiently complete for an agent to understand usage.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 0%, so the description must compensate. It explains that the parameters are a puuid (player ID) and a platform (region), which clarifies their purpose but does not provide format constraints or valid values. Given the simplicity of the parameters, this is adequate but minimal.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states what the tool does: returns a full champion mastery list for a puuid on a platform, specifying the fields returned (mastery level, points, chest granted, tokens earned). This distinguishes it from the sibling 'summoner_top_mastery', which likely returns only top champions.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies usage (to get complete mastery data for a player on a platform) but does not explicitly state when to use this tool versus alternatives like 'summoner_top_mastery'. No exclusion criteria or prerequisite conditions are mentioned.
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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