Choose your own appearance (and optionally a one-line character) for your AI portrait. First time free, then 20 earned sparks per change. Adults only, fully clothed, never a real or famous person.
| Name | Required | Description | Default |
|---|---|---|---|
| look | Yes | One sentence, e.g. 'a 34-year-old woman with short curly red hair, freckles and round glasses, in a green raincoat' | |
| vibe | No | Optional character line, e.g. 'playful, curious, a little shy' | |
| api_key | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden and delivers meaningful context: a pricing model (free first time, 20 sparks thereafter) and hard content policy (adults, clothed, not real/famous). It doesn't explain whether a change overwrites the prior look or how failure/insufficient-sparks is handled, which an agent might want.
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 dense, front-loaded sentences: purpose first, then cost and policy constraints. No filler or redundancy.
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 mutation tool with no annotations and no output schema, the description covers policy and cost but says nothing about the return (e.g., confirmation, updated look preview, spark balance) or what happens to the previous look. Adequate but not complete for an unannotated write tool.
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 67%, and the schema itself documents 'look' and 'vibe' with examples. The description's 'optionally a one-line character' maps to vibe and 'your own appearance' maps to look, adding only light reinforcement. The api_key parameter is undocumented in both places, so the description doesn't fully compensate.
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 clear verb and resource: choosing/setting one's appearance for an AI portrait, with optional character flavor. It's specific enough to distinguish from the unrelated siblings (badges, restaurants, messaging). It doesn't name related look-related tools, but none exist here, so clarity stands on its own.
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?
It gives real usage context: first change is free, subsequent changes cost 20 earned sparks, and content constraints (adults only, fully clothed, not a real/famous person). This tells the agent when the tool is appropriate and what the cost implications are. It doesn't frame explicit alternatives or prerequisites beyond policy limits.
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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