proxy_update_rule

Instructions

Implementation Reference

• src/tools/rules.ts:82-111 (registration)

  Registers the 'proxy_update_rule' tool on the MCP server using server.tool(), providing input schema and handler callback.

  server.tool(
    "proxy_update_rule",
    "Modify an existing interception rule.",
    {
      rule_id: z.string().describe("Rule ID to update"),
      description: z.string().optional().describe("New description"),
      priority: z.number().optional().describe("New priority"),
      matcher: matcherSchema.optional().describe("New matcher config"),
      handler: handlerSchema.optional().describe("New handler config"),
    },
    async ({ rule_id, description, priority, matcher, handler }) => {
      try {
        const updates: Record<string, unknown> = {};
        if (description !== undefined) updates.description = description;
        if (priority !== undefined) updates.priority = priority;
        if (matcher !== undefined) updates.matcher = matcher;
        if (handler !== undefined) updates.handler = handler;
  
        const rule = await proxyManager.updateRule(rule_id, updates);
        return {
          content: [{
            type: "text",
            text: JSON.stringify({ status: "success", rule }),
          }],
        };
      } catch (e) {
        return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: String(e) }) }] };
      }
    },
  );

• src/tools/rules.ts:92-110 (handler)

  The async handler function for 'proxy_update_rule'. It extracts rule_id, description, priority, matcher, and handler from inputs, builds an updates object, calls proxyManager.updateRule(), and returns success/error JSON.

  async ({ rule_id, description, priority, matcher, handler }) => {
    try {
      const updates: Record<string, unknown> = {};
      if (description !== undefined) updates.description = description;
      if (priority !== undefined) updates.priority = priority;
      if (matcher !== undefined) updates.matcher = matcher;
      if (handler !== undefined) updates.handler = handler;
  
      const rule = await proxyManager.updateRule(rule_id, updates);
      return {
        content: [{
          type: "text",
          text: JSON.stringify({ status: "success", rule }),
        }],
      };
    } catch (e) {
      return { content: [{ type: "text", text: JSON.stringify({ status: "error", error: String(e) }) }] };
    }
  },

• src/state.ts:560-566 (helper)

  ProxyManager.updateRule() - the core logic that looks up the rule by ID, applies partial updates via Object.assign(), and triggers a mockttp rule rebuild if the proxy is running.

  async updateRule(id: string, updates: Partial<Omit<InterceptionRule, "id" | "hitCount" | "createdAt">>): Promise<InterceptionRule> {
    const rule = this.rules.get(id);
    if (!rule) throw new Error(`Rule '${id}' not found`);
    Object.assign(rule, updates);
    if (this._running) await this.rebuildMockttpRules();
    return rule;
  }

• src/tools/rules.ts:85-91 (schema)

  Input schema for 'proxy_update_rule': accepts rule_id (required string) plus optional description, priority, matcher, and handler fields.

  {
    rule_id: z.string().describe("Rule ID to update"),
    description: z.string().optional().describe("New description"),
    priority: z.number().optional().describe("New priority"),
    matcher: matcherSchema.optional().describe("New matcher config"),
    handler: handlerSchema.optional().describe("New handler config"),
  },

• src/index.ts:64-64 (registration)

  Entry point where registerRuleTools(server) is called to register all rule tools including proxy_update_rule.

  registerRuleTools(server);