Encrypt a room key to a recipient's x25519 public key, outputting a secure mailbox line. Warns to verify the key out-of-band.
Create a room key and seal it to a recipient's x25519 public key, producing one e2e1 mailbox line. Always warns that the recipient key needs out-of-band corroboration.
| Name | Required | Description | Default |
|---|---|---|---|
| room | No | Optional; random if omitted. | |
| recipient_x25519 | Yes | base64url public key |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It does add value by revealing the output form ('one e2e1 mailbox line') and a consistent behavior ('Always warns...'). However, it does not clarify whether this operation writes to a mailbox, whether it is reversible, what happens with invalid keys, or whether authentication or permissions are required.
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 tight sentences deliver the core action, the output, and an important warning. The main behavior is front-loaded, and every clause earns its place. There is no fluff or restatement of the tool name.
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 two-parameter tool with no output schema, the description covers the essential invocation context: what gets sealed, to which key, and what the result looks like. The main gaps are unclear side-effect/delivery semantics and lack of sibling-selection context, but those are less critical given the small surface area.
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 description coverage is 100%, so the baseline is 3. The description reinforces that recipient_x25519 is the sealing target, but it does not add meaning beyond the schema's 'base64url public key' and 'Optional; random if omitted' notes. No new constraints, formats, or edge-case guidance are provided.
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 uses a specific verb and resource: 'Create a room key and seal it to a recipient's x25519 public key.' It also names the concrete output, 'one e2e1 mailbox line', which distinguishes it from siblings like open_sealed or encrypt_line. This is immediately actionable and unambiguous.
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 does not say when to choose this tool over alternatives such as open_sealed, encrypt_line, or decrypt_line. It implies a purpose but provides no explicit context, prerequisites, or exclusions. The only conditional note is about the recipient key needing corroboration, which is operational caution rather than selection guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.