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waha_block_contact

Block unwanted WhatsApp contacts to prevent further communication. Specify the contact ID to restrict messages and calls from that user.

Instructions

Block a contact.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
contactIdYesContact ID to block (format: number@c.us)

Implementation Reference

  • MCP tool handler for 'waha_block_contact'. Validates input, calls WAHAClient.blockContact, returns success response.
    private async handleBlockContact(args: any) {
      const contactId = args.contactId;
    
      if (!contactId) {
        throw new Error("contactId is required");
      }
    
      await this.wahaClient.blockContact(contactId);
    
      return {
        content: [
          {
            type: "text",
            text: `Successfully blocked contact ${contactId}.`,
          },
        ],
      };
    }
  • src/index.ts:958-971 (registration)
    Tool registration entry in listTools response, including name, description, and input schema.
    {
      name: "waha_block_contact",
      description: "Block a contact.",
      inputSchema: {
        type: "object",
        properties: {
          contactId: {
            type: "string",
            description: "Contact ID to block (format: number@c.us)",
          },
        },
        required: ["contactId"],
      },
    },
  • Input schema definition for the waha_block_contact tool.
    inputSchema: {
      type: "object",
      properties: {
        contactId: {
          type: "string",
          description: "Contact ID to block (format: number@c.us)",
        },
      },
      required: ["contactId"],
    },
  • WAHAClient helper method that sends POST request to WAHA API endpoint /api/contacts/block to block the contact.
    async blockContact(contactId: string): Promise<void> {
      if (!contactId) {
        throw new WAHAError("contactId is required");
      }
    
      const body = {
        contactId,
        session: this.session,
      };
    
      await this.request<void>("/api/contacts/block", {
        method: "POST",
        body: JSON.stringify(body),
      });
    }
Behavior2/5

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

With no annotations provided, the description carries full burden but only states the action without disclosing behavioral traits. It doesn't mention whether blocking is reversible, what permissions are required, how it affects chat functionality, or what happens to existing messages. For a mutation tool with zero annotation coverage, this is inadequate.

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?

The description is a single, direct sentence with zero wasted words. It's appropriately sized for a simple action and front-loads the essential information immediately.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a mutation tool with no annotations and no output schema, the description is incomplete. It doesn't explain the consequences of blocking, potential errors, or what the tool returns. Given the complexity of a blocking operation in a messaging context, more behavioral context is needed.

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%, so the schema already documents the 'contactId' parameter with its format. The description doesn't add any meaning beyond what the schema provides, such as explaining where to find the contactId or what happens if an invalid ID is provided. Baseline 3 is appropriate when schema does the heavy lifting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action ('Block') and resource ('a contact'), making the purpose immediately understandable. However, it doesn't differentiate from its sibling 'waha_unblock_contact' or explain what 'blocking' means in this context (e.g., preventing messages from that contact).

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

Usage Guidelines2/5

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

No guidance is provided about when to use this tool versus alternatives like 'waha_unblock_contact' or other contact management tools. The description lacks context about prerequisites (e.g., the contact must exist) or typical use cases for blocking contacts.

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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