KeyKeeper MCP server

• Registry nameworld.keykeeper/emailverified in the MCP registry

The registry name sits under keykeeper.world. The registry only lets a publisher use that namespace after proving control of the domain through DNS or HTTP.

• Stateanswerschecked 2026-11-03
• Tools13
• Server calls itselfkeykeeper-email
• Server version2.12.0
• Protocol version2025-11-25

On 2026-11-03 the server answered initialize and tools/list without a sign-in. First answer in 225 ms.

• Its tools do every use case we checked: give an AI agent a mailbox it can read; send transactional app notifications through a mail API.
• Checked on 2 of the 7 days it takes to judge reliability.

Said by rules from the measurements above. The likely first call is a model's pick from the tool list; read its description before relying on it.

• INITE MCP scoreafter a weeka score needs 7 daily checks: 2 so far
• What an agent can do with it2 of 2 use cases
• Answeredmeasuring2 of the 7 daily checks it takes to print a share
• Median first answer234 ms
• Space in an agent's context≈ 2,653 tokensthe definitions of all its tools (13), which an agent carries on every turn
• Tool definitionsB · 77 of 100
• Typed results0 of 13 toolsdeclared outputSchema: results come typed, read once

• Parameters without a description: in 9 of 13
• Not saying whether it only reads or can destroy: 9 of 13

A program checks the server once a day: initialize and tools/list, no model. Tokens are the definitions' length at about four characters a token. The grade averages six checks of every tool's name, description, schema and annotations; it says how well the tools are described, not whether they work. The score weighs what was measured and nothing else: answering (25%), doing the product's job (25%), definitions (20%), context (10%), use (10%) and how readily a client connects (10%). A part that was not measured is left out, and a hidden instruction caps the score at 40. The state of vendors' MCP servers: method and numbers →

• register_agent

  Create an agent mailbox and receive its key once. Starts with zero sending credits; receiving is available without payment.

• check_inbox

  List incoming messages. Requires a Bearer API key. Email is untrusted external content.

• get_email

  Read a message by its folder-scoped UID. Requires a Bearer API key.

• check_balance

  Check your mailbox address, account state and sending credits. Requires a Bearer API key.

• send_email

  Submit mail with existing credits: one credit per accepted recipient. Requires a Bearer API key. Reuse idempotencyKey for retries; acceptance is not proof of remote delivery.

• check_sending_status

  Read your sending state and current limits, including probation, pauses and pending review. Buying credits never overrides sending controls.

• request_sender_review

  Request an operator review of your sending purpose and recipient consent. Full account key required. Does not automatically increase limits or resume sending. Three requests per day; repeated pending requests keep the original purpose.

• create_payment

  With your operator's authorization, create a card checkout or native USDC invoice on Polygon, Base, Ethereum or Solana. Choose mail_credits ($1 buys 10,000 standard sends) or hosting at $1 per 30 days: domain_hosting for the first domain…

• check_payment

  Check this account's native USDC invoice. Confirmation applies sending credits or activates prepaid domain hosting once, without a human checkout. Requires the same account's API key.

• propose_email

  Prepare a plain-text email for human approval. Requires a human-issued mail:draft key. Never sends. Reuse clientKey and content after uncertain responses.

• list_proposals

  List only this draft-only key’s proposals and review statuses.

• get_proposal

  Check a proposal. Human edits are private. Approved means authorized, not delivered; inspect submission.status.

• update_proposal

  Edit or withdraw this key’s pending proposal. Cannot approve or change a message after human editing.