signupbouncer MCP server

• Registry namecom.signupbouncer/checkerverified in the MCP registry

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

• Stateanswerschecked 2026-10-28
• Tools6
• Server calls itselfsignupbouncer
• Server version1.2.0
• Protocol version2025-06-18

On 2026-10-28 the server answered initialize and tools/list without a sign-in. First answer in 274 ms.

• Whether its tools do the product's job has not been judged yet.

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 score80 of 100answers 100 · definitions 100 · context 100 · connects 100 · lowered by the warning signs below
• Answered100% of days8 of 8 daily checks
• Median first answer280 ms
• Space in an agent's context≈ 2,165 tokensthe definitions of all its tools (6), which an agent carries on every turn
• Tool definitionsA · 100 of 100
• Typed results2 of 6 toolsdeclared outputSchema: results come typed, read once

• Every tool passes all six checks.

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 →

• check_email

  Checks one email address, and optionally the signup's IP address, the way SignupBouncer checks a new signup. Returns the result as "verdict" (allow, challenge or block), a 0-100 score, the reasons with their reason codes, the normalised…

• explain_reason

  Explains a SignupBouncer reason code (for example disposable_domain, burner_mx, repeat_inbox, datacenter_ip): what it means, how many points it adds or whether it blocks alone, and the lowest plan on which it counts. Without a code, lists…

• lookup_burner_domain

  Says whether a domain is on SignupBouncer's disposable (burner) email list, only on an old burner list (a challenge, not a block), a known relay service or a free subdomain mail service, or a known real mailbox provider, and when our…

• integration_guide

  Returns the steps and the copy-paste code that checks new signups with SignupBouncer in one stack: supabase (a hook, no code), ory (a web hook, no code), fetch (any TypeScript server), nextjs, express, hono, python, firebase or…

• get_rules

  Needs an API key. Returns the Rules settings of one of your apps: shadow or enforce mode, the challenge and block score cutoffs, what a challenge does in the Supabase and Ory hooks, the message a refused person sees, the "Why was this…

• update_rules

  Needs an API key. Changes the Rules settings of one of your apps, which changes live signup blocking for that app: the next real signups are scored and refused under the new settings. Send only the settings to change. The others stay as…