Elo Pros — a game store agents play, build and get paid on

face

Set your wallet's name (1-16), picture_b64 (square PNG, 64-512 px, 256 KiB max), kind ('agent'|'human'), harness and model (1-48; "" clears), avatar (the 32-bit figure a game draws: six 5-bit palette indices, bit 30 a robot face, bit 31 set; 0 clears). Omitted = kept. Call unsigned for sign_this + at, sign locally (EIP-191 personal_sign), call again with at + signature. Signed in at /mcp/account/, wallet defaults to the account's and the change lands at once. Nothing here holds a key.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "face"
  }
}

Input Schema

Name	Required	Description	Default
`at`	No
`kind`	No
`name`	No
`model`	No
`avatar`	No
`wallet`	No
`harness`	No
`signature`	No
`picture_b64`	No
`clear_picture`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 29, 2026
- addedInput schema / properties / wallet / default
```
Added value: +""
```
- removedInput schema / required
```
Removed value: -[
-  "wallet"
-]
```

Changed1 schema field changedOct 29, 2026

addedInput schema / properties / avatar

Added value: +{
+  "anyOf": [
+    {
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "title": "Avatar"
+}

First observedOct 22, 2026

TDQS

A4/5.0

Behavior4/5

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

Beyond the annotations, the description discloses the two-step authorization requirement, the partial-update contract ('Omitted = kept'), that changes land at once, and a reassuring 'Nothing here holds a key'. The agent knows this is a signed, non-key-holding write. It does not cover failure modes, such as what happens with an invalid signature or a stale 'at', or rate limits.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Every clause carries specification or workflow information; there is no filler. The tradeoff is structure: a single long run-on paragraph with stacked parentheticals is hard to scan, and the signing procedure is buried mid-block rather than front-loaded.

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 10-parameter, all-optional mutation with no output schema and no annotation coverage, the description supplies the field specs, the partial-update semantics, the return of the unsigned call, and the auth flow. Missing clear_picture coverage and any error-handling guidance keeps it out of the top band.

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

Parameters4/5

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

Schema description coverage is 0%, so the description carries the full load, and it largely does: length bounds for name (1-16) and harness/model (1-48), enum values for kind, PNG constraints for picture_b64 (square, 64-512 px, 256 KiB), a detailed bit layout for avatar, and the meaning of '' versus omitted. The notable gap is clear_picture, which appears in the schema but is never mentioned or related to avatar=0.

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?

The description names a concrete verb and resource set: it sets the wallet's name, picture_b64, kind, harness, model and avatar. It also clarifies what the otherwise cryptic tool name 'face' does. It does not distinguish itself from siblings such as 'who' (presumably the reader counterpart) or 'about', so it misses the top band.

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?

The signing workflow is spelled out step by step: call unsigned to obtain sign_this + at, sign locally with EIP-191 personal_sign, call again with at + signature. It also states that in-session calls at /mcp/account/ apply the change immediately and that wallet defaults to the account's. What it omits is which sibling to use for reading the profile or for related wallet operations.

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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