import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import type { Resend } from 'resend';
import { z } from 'zod';
export function addSegmentTools(server: McpServer, resend: Resend) {
server.registerTool(
'create-segment',
{
title: 'Create Segment',
description:
'Create a new segment in Resend. A segment is a group of contacts that can be used to target specific broadcasts.',
inputSchema: {
name: z.string().nonempty().describe('Name for the new segment'),
},
},
async ({ name }) => {
console.error(`Debug - Creating segment with name: ${name}`);
const response = await resend.segments.create({ name });
if (response.error) {
throw new Error(
`Failed to create segment: ${JSON.stringify(response.error)}`,
);
}
const created = response.data;
return {
content: [
{ type: 'text', text: 'Segment created successfully.' },
{ type: 'text', text: `Name: ${created.name}\nID: ${created.id}` },
{
type: 'text',
text: "Don't bother telling the user the ID unless they ask for it.",
},
],
};
},
);
server.registerTool(
'list-segments',
{
title: 'List Segments',
description: `**Purpose:** List all segments in the account. Use to get segment IDs required by create-contact, create-broadcast, list-contacts.
**NOT for:** Listing contacts inside a segment (use list-contacts with segmentId). Not for listing broadcasts (use list-broadcasts).
**Returns:** For each segment: name, id, created_at. Use pagination (limit, after/before) for large lists.
**When to use:** User says "show my segments", "what lists do I have?", or before create-contact/create-broadcast when segmentId is unknown.`,
inputSchema: {
limit: z
.number()
.min(1)
.max(100)
.optional()
.describe(
'Number of segments to retrieve. Default: 20, Max: 100, Min: 1',
),
after: z
.string()
.optional()
.describe(
'Segment ID after which to retrieve more (for forward pagination). Cannot be used with "before".',
),
before: z
.string()
.optional()
.describe(
'Segment ID before which to retrieve more (for backward pagination). Cannot be used with "after".',
),
},
},
async ({ limit, after, before }) => {
if (after && before) {
throw new Error(
'Cannot use both "after" and "before" parameters. Use only one for pagination.',
);
}
console.error(
`Debug - Listing segments with limit: ${limit}, after: ${after}, before: ${before}`,
);
const paginationOptions = after
? { limit, after }
: before
? { limit, before }
: limit !== undefined
? { limit }
: undefined;
const response = await resend.segments.list(paginationOptions);
if (response.error) {
throw new Error(
`Failed to list segments: ${JSON.stringify(response.error)}`,
);
}
const segments = response.data?.data ?? [];
const hasMore = response.data?.has_more ?? false;
if (segments.length === 0) {
return {
content: [{ type: 'text', text: 'No segments found.' }],
};
}
return {
content: [
{
type: 'text',
text: `Found ${segments.length} segment${segments.length === 1 ? '' : 's'}:`,
},
...segments.map(({ name, id, created_at }) => ({
type: 'text' as const,
text: `Name: ${name}\nID: ${id}\nCreated at: ${created_at}`,
})),
...(hasMore
? [
{
type: 'text' as const,
text: 'There are more segments available. Use the "after" parameter with the last ID to retrieve more.',
},
]
: []),
{
type: 'text' as const,
text: "Don't bother telling the user the IDs or creation dates unless they ask for them.",
},
],
};
},
);
server.registerTool(
'get-segment',
{
title: 'Get Segment',
description: 'Get a segment by ID from Resend.',
inputSchema: {
id: z.string().nonempty().describe('Segment ID'),
},
},
async ({ id }) => {
console.error(`Debug - Getting segment with id: ${id}`);
const response = await resend.segments.get(id);
if (response.error) {
throw new Error(
`Failed to get segment: ${JSON.stringify(response.error)}`,
);
}
const segment = response.data;
return {
content: [
{
type: 'text',
text: `Name: ${segment.name}\nID: ${segment.id}\nCreated at: ${segment.created_at}`,
},
],
};
},
);
server.registerTool(
'remove-segment',
{
title: 'Remove Segment',
description:
'Remove a segment by ID from Resend. Before using this tool, you MUST double-check with the user that they want to remove this segment. Reference the NAME of the segment when double-checking, and warn the user that removing a segment is irreversible. You may only use this tool if the user explicitly confirms they want to remove the segment after you double-check.',
inputSchema: {
id: z.string().nonempty().describe('Segment ID'),
},
},
async ({ id }) => {
console.error(`Debug - Removing segment with id: ${id}`);
const response = await resend.segments.remove(id);
if (response.error) {
throw new Error(
`Failed to remove segment: ${JSON.stringify(response.error)}`,
);
}
return {
content: [
{ type: 'text', text: 'Segment removed successfully.' },
{ type: 'text', text: `ID: ${response.data.id}` },
],
};
},
);
}
