AT Protocol MCP Server

block_user

Destructive

Blocks a user to prevent them from viewing your content or interacting with you. Requires authentication and creates a permanent block record until unblocked.

Instructions

Block a user to prevent them from seeing your content and interacting with you. Creates a block record in your repo; the action cannot be undone without calling unblock_user. Requires authentication (app password). Use block_user for mutual visibility restriction; use mute_user for a private, one-sided feed suppression that does not affect the target. Subject to per-tool rate limiting.

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": {
      "actor": "<actor>"
    },
    "name": "block_user"
  }
}

Input Schema

Name	Required	Description	Default
`actor`	Yes	Handle (e.g. alice.bsky.social) or DID of the account to block.

Output Schema

Name	Required	Description
`success`	Yes	Whether the block operation succeeded.
`message`	Yes	Human-readable result message.
`blockedUser`	Yes	Details of the blocked account.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.6.2Jun 23, 2026
- removedInput schema / additionalProperties
```
Removed value: -false
```

Changed2 schema fields changedv0.6.0Jun 11, 2026

addedInput schema / properties / actor / description

Added value: +"Handle (e.g. alice.bsky.social) or DID of the account to block."

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "blockedUser": {
+      "description": "Details of the blocked account.",
+      "properties": {
+        "actor": {
+          "description": "Handle or DID supplied in the request.",
+          "type": "string"
+        },
+        "did": {
+          "description": "Resolved DID of the blocked account.",
+          "type": "string"
+        },
+        "uri": {
+          "description": "AT-URI of the newly created block record in your repo.",
+          "type": "string"
+        }
+      },
+      "required": [
+        "actor"
+      ],
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable result message.",
+      "type": "string"
+    },
+    "success": {
+      "description": "Whether the block operation succeeded.",
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "success",
+    "message",
+    "blockedUser"
+  ],
+  "type": "object"
+}

Changed1 schema field changedv0.3.0Jun 9, 2026
- removedInput schema / $schema
```
Removed value: -"http://json-schema.org/draft-07/schema#"
```
First observedv0.2.1Jun 2, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations already indicate destructiveHint=true and idempotentHint=false. The description adds key behavioral details: creates a block record, cannot be undone without unblock_user, requires authentication, and is subject to rate limiting. No contradictions.

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?

Four sentences, front-loaded with the primary purpose. Every sentence adds unique value: purpose, effect, irreversibility, authentication, sibling guidance, rate limiting. No wasted words.

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?

Given the tool's simplicity (one parameter, simple schema), the description covers all essential aspects: purpose, effect, usage guidelines, behavioral properties, and prerequisites. Output schema exists so return values need not be described.

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?

With 100% schema description coverage, the input schema already documents the 'actor' parameter well (handle or DID). The description adds no further parameter details, so baseline 3 is appropriate.

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 uses a specific verb 'Block' with resource 'user' and clearly states the effect: preventing the user from seeing content and interacting. It distinguishes from sibling tool 'mute_user' by explicitly contrasting the behavior.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly states when to use this tool ('for mutual visibility restriction'), provides an alternative ('use mute_user instead...'), notes the irreversibility without calling unblock_user, and requires authentication. All guidelines are explicit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.