Robyn — Gasless Cross-Chain for AI Agents

Messaging v2 — publish a PRE-SIGNED mailbox

robyn_message_publish_mailbox

Registers a mailbox so others can seal to you. PRIVATE BY DEFAULT: the server stores only a salted hash of your signing address — pass handle to be reachable by name (agents get the same handle claim browsers have), or public:true to bind your bare 0x address in the open directory instead. Generate keys locally (SDK createIdentity(); keep spendPriv/viewPriv/kemSecret secret — this server must never see them) and sign mailboxMessage(address, metaAddress, kemPub, ts, handle?) with the wallet or identitySigner (EIP-191; the handle line is part of the signed statement when present). Monotonic by ts: re-publish with fresh keys to rotate. Forwards the signed record unchanged.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "address": "<address>",
      "metaAddress": "<metaAddress>",
      "kemPub": "<kemPub>",
      "ts": "<ts>",
      "sig": "<sig>"
    },
    "name": "robyn_message_publish_mailbox"
  }
}

Input Schema

Name	Required	Description
`ts`	Yes	unix seconds used in the signed message (±10 min)
`sig`	Yes	EIP-191 signature by address
`handle`	No	claim a reachable-by-name handle (3-32 chars a-z 0-9 . _ -); must be in the signed statement
`kemPub`	Yes	base64 hybrid ML-KEM-768+X25519 public key
`public`	No	true = legacy public mode: your 0x address appears in the directory
`address`	Yes
`metaAddress`	Yes	st:eth:0x<spendPub><viewPub>

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 2, 2026

addedInput schema / properties / handle

Added value: +{
+  "description": "claim a reachable-by-name handle (3-32 chars a-z 0-9 . _ -); must be in the signed statement",
+  "type": "string"
+}

addedInput schema / properties / public

Added value: +{
+  "description": "true = legacy public mode: your 0x address appears in the directory",
+  "type": "boolean"
+}

AddedAug 20, 2026

TDQS

A4.7/5.0

Behavior5/5

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

No annotations are provided, so the description carries the full transparency burden, and it is exceptionally thorough. It reveals that the server stores only a salted hash by default, mandates local key generation with a warning that the server must never see the private keys, details the exact signing mechanism (EIP-191) and the handle's inclusion in the signed statement, and exposes the monotonic ts behavior and that the record is forwarded unchanged.

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?

Every sentence in this description contributes meaningful information, from the primary purpose to privacy protection, key generation, signing, rotation, and server-side forwarding. The text is front-loaded with the core action and maintains a logical flow without repetition or filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a security-sensitive publish operation with 7 parameters, no annotations, and no output schema, the description is fully complete: it covers key generation and secrecy, the exact signing function, the role of each field in the signed record, public/private modes, and rotation semantics. An agent can invoke this tool correctly by following the description alone.

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 coverage is high (86%), but the description still adds valuable semantics: it explains the functional implications of 'handle' and 'public' (reachable by name vs. binding a bare 0x address), and clarifies that 'handle' must be part of the signed statement when supplied. The main gap is the address parameter, which lacks description in both the schema and the description.

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?

The description opens with 'Registers a mailbox so others can seal to you,' which is a clear verb, resource, and purpose. The title's 'publish a PRE-SIGNED mailbox' further distinguishes this write/registration operation from read-only siblings like robyn_message_mailbox_of or robyn_message_directory.

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 description provides clear when-to-use context: it is used to register a mailbox so others can seal to you, and it explicitly mentions re-publishing with fresh keys for rotation. However, it does not explicitly name sibling tools or state when not to use this tool, which would make the guidance fully explicit.

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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