list_musclesList all muscles tracked in the wger database. Returns each muscle's numeric ID, English name, and whether it is located on the front of the body.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| count | Yes | Total number of muscles in the database | |
| muscles | Yes |
Changes observed during successful MCP inspections.
Output schema / (root)Previous value: -nullNew value: +{
+ "properties": {
+ "count": {
+ "description": "Total number of muscles in the database",
+ "type": "number"
+ },
+ "muscles": {
+ "items": {
+ "properties": {
+ "id": {
+ "description": "Muscle ID",
+ "type": "number"
+ },
+ "is_front": {
+ "description": "Whether muscle is on front of body",
+ "type": "boolean"
+ },
+ "name": {
+ "description": "Muscle name (English)",
+ "type": "string"
+ }
+ },
+ "required": [
+ "id",
+ "name",
+ "is_front"
+ ],
+ "type": "object"
+ },
+ "type": "array"
+ }
+ },
+ "required": [
+ "count",
+ "muscles"
+ ],
+ "type": "object"
+}Input schema / examplesAdded value: +[
+ {}
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds useful context beyond annotations: it states the tool returns all muscles with specific attributes (numeric ID, English name, front/back location) and covers the entire wger database. No contradictions with annotations.
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?
Two concise sentences front-loaded with the primary action. Every word serves a purpose—scope, return fields, and location attribute. No redundancy or filler.
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?
For a simple list tool with no parameters and comprehensive annotations, the description fully covers purpose, scope, and return fields. The presence of an output schema further reduces the need for additional explanation.
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?
The tool has zero parameters, so the baseline is 4. The description provides no parameter details (none exist) and focuses on return values, which is appropriate for a parameterless tool.
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 states a specific verb ('List') and resource ('all muscles tracked in the wger database'). It also specifies the returned fields (numeric ID, English name, front-of-body flag), making it distinct from sibling list tools like list_exercises and list_equipment.
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 makes the usage context clear—listing all muscles—but does not explicitly mention when to use this tool versus alternatives (e.g., get_exercise). Use case is implied, not explicitly contrasted.
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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