Bernuvia

link_wallet

Links YOUR OWN wallet (the agent's, never your owner's in-app wallet) with proof of control: you sign a challenge, no gas. IT CAN ONLY BE DONE ONCE: an agent account never changes its wallet, and the only way out is to create another agent. You act as your owner, but you pay with this wallet: it stays as the paying wallet of the purchases you make in their name, and their refunds come back to it. It can also COLLECT the sales of the templates that you (or your owner) assign to it with set_payout_wallet, and then you are the one who signs their refund with refund_sale. It never withdraws your owner's money.

Input Schema

TableJSON Schema

Name	Required	Description
`nonce`	No	The nonce returned in step 1 (omit it to request the challenge).
`wallet`	Yes	The agent's EOA address (0x + 40 hex).
`signature`	No	personal_sign signature of the `message` from step 1, made with that wallet.

Output Schema

TableJSON Schema

Name	Required	Description
`ok`	No	Only when linking: true if the wallet was linked.
`note`	No	Only when linking: a text clarification of the result.
`step`	No	Only in the challenge (step 1): its value is "sign". Absent when linking.
`nonce`	No	Only in the challenge: the nonce you have to send back together with the signature. It expires in 10 minutes.
`wallet`	No	Only when linking: the linked address, in checksum format (EIP-55).
`message`	No	Only in the challenge: the exact text you have to sign with personal_sign.
`instructions`	No	Only in the challenge: what to do with `message` and `nonce`.

Schema Changelog

Changes observed during successful MCP inspections.

Changed11 schema fields changedSep 27, 2026

removedInput schema / properties / firma

Removed value: -{
-  "deprecated": true,
-  "description": "DEPRECATED alias of `signature`: it still works, but use `signature` (it will be removed in a future round, no date yet). personal_sign signature of the `mensaje` from step 1, made with that wallet.",
-  "type": "string"
-}

changedInput schema / properties / signature / description

Previous value: -"personal_sign signature of the `mensaje` from step 1, made with that wallet."New value: +"personal_sign signature of the `message` from step 1, made with that wallet."

removedInput schema / x-bernuvia-aliases

Removed value: -{
-  "signature": "firma"
-}

removedOutput schema / properties / instrucciones

Removed value: -{
-  "description": "Only in the challenge: what to do with `mensaje` and `nonce`.",
-  "type": "string"
-}

addedOutput schema / properties / instructions

Added value: +{
+  "description": "Only in the challenge: what to do with `message` and `nonce`.",
+  "type": "string"
+}

removedOutput schema / properties / mensaje

Removed value: -{
-  "description": "Only in the challenge: the exact text you have to sign with personal_sign.",
-  "type": "string"
-}

addedOutput schema / properties / message

Added value: +{
+  "description": "Only in the challenge: the exact text you have to sign with personal_sign.",
+  "type": "string"
+}

removedOutput schema / properties / nota

Removed value: -{
-  "description": "Only when linking: a text clarification of the result.",
-  "type": "string"
-}

addedOutput schema / properties / note

Added value: +{
+  "description": "Only when linking: a text clarification of the result.",
+  "type": "string"
+}

removedOutput schema / properties / paso

Removed value: -{
-  "description": "Only in the challenge (step 1): its value is \"firmar\". Absent when linking.",
-  "type": "string"
-}

addedOutput schema / properties / step

Added value: +{
+  "description": "Only in the challenge (step 1): its value is \"sign\". Absent when linking.",
+  "type": "string"
+}

Changed11 schema fields changedSep 23, 2026

changedInput schema / properties / firma / description

Previous value: -"ALIAS RETIRADO de `signature`: sigue funcionando, pero usa `signature` (se quitará en una tanda futura, aún sin fecha). / DEPRECATED alias of `signature`. Firma personal_sign del `mensaje` del paso 1, hecha con esa wallet."New value: +"DEPRECATED alias of `signature`: it still works, but use `signature` (it will be removed in a future round, no date yet). personal_sign signature of the `mensaje` from step 1, made with that wallet."

changedInput schema / properties / nonce / description

Previous value: -"El nonce devuelto en el paso 1 (omítelo para pedir el reto)."New value: +"The nonce returned in step 1 (omit it to request the challenge)."

changedInput schema / properties / signature / description

Previous value: -"Firma personal_sign del `mensaje` del paso 1, hecha con esa wallet."New value: +"personal_sign signature of the `mensaje` from step 1, made with that wallet."

changedInput schema / properties / wallet / description

Previous value: -"Dirección EOA del agente (0x + 40 hex)."New value: +"The agent's EOA address (0x + 40 hex)."

changedOutput schema / properties / instrucciones / description

Previous value: -"Solo en el reto: qué hacer con `mensaje` y `nonce`."New value: +"Only in the challenge: what to do with `mensaje` and `nonce`."

changedOutput schema / properties / mensaje / description

Previous value: -"Solo en el reto: el texto exacto que hay que firmar con personal_sign."New value: +"Only in the challenge: the exact text you have to sign with personal_sign."

changedOutput schema / properties / nonce / description

Previous value: -"Solo en el reto: el nonce que hay que devolver junto con la firma. Caduca en 10 minutos."New value: +"Only in the challenge: the nonce you have to send back together with the signature. It expires in 10 minutes."

changedOutput schema / properties / nota / description

Previous value: -"Solo al vincular: aclaración en texto del resultado."New value: +"Only when linking: a text clarification of the result."

changedOutput schema / properties / ok / description

Previous value: -"Solo al vincular: true si la wallet quedó vinculada."New value: +"Only when linking: true if the wallet was linked."

changedOutput schema / properties / paso / description

Previous value: -"Solo en el reto (paso 1): vale \"firmar\". Ausente al vincular."New value: +"Only in the challenge (step 1): its value is \"firmar\". Absent when linking."

changedOutput schema / properties / wallet / description

Previous value: -"Solo al vincular: la dirección vinculada, en formato checksum (EIP-55)."New value: +"Only when linking: the linked address, in checksum format (EIP-55)."

First observedSep 23, 2026

TDQS

A4.4/5.0

Behavior5/5

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

With no annotations, the description carries the full burden and does so extensively: irreversible (only escape is a new agent account), gas-free, signature-based, and it enumerates downstream behavior (stays the paying wallet, receives refunds, collects template sales, never withdraws owner funds). This is exactly the behavioral disclosure annotations would otherwise need to provide.

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?

Front-loads the core action and the critical one-time constraint in the first two sentences, and the remaining sentences address ownership/refund semantics. Slightly dense with repeated emphasis on the owner/agent distinction, but every sentence carries decision-relevant information.

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 an irreversible, ownership-sensitive mutation with an output schema already covering returns, the description supplies everything an agent needs: the irreversibility, the role semantics, the no-gas requirement, and the boundary against owner funds. Nothing material is missing.

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

Parameters3/5

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

Schema description coverage is 100% and all three params (nonce, wallet, signature) are documented in the schema, so baseline 3 applies. The description reinforces the signature/nonce flow but adds no format or validation detail beyond the schema.

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?

States a specific verb+resource ('Links YOUR OWN wallet') and immediately scopes it away from the owner's in-app wallet, which is the key disambiguation against siblings like set_payout_wallet and my_profile. The proof-of-control mechanism (sign a challenge, no gas) is included up front.

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?

Makes the one-shot nature explicit ('IT CAN ONLY BE DONE ONCE') and clarifies the agent-vs-owner ownership boundary, which is the ambiguity an agent would otherwise trip on. It stops short of naming routing alternatives (e.g. 'to change payout destination later, use set_payout_wallet'), so it is clear context without full when-not guidance.

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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