mongodb-memory-mcp: Skill for Claude Code

Adding an MCP tool

A tool is five files, always in this order. Doing them out of order produces a tool the SDK will not register or, worse, one that skips cross-field validation.

Read src/mcp/tools/store-content.ts and src/mcp/tools/shared.ts first — they are the reference implementation, and everything below matches them.

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Step 1 — Decide whether the service needs a new method

Transports hold no business logic (src/services/types.ts says so and means it). A tool validates input, calls exactly one KnowledgeService method, and formats the result.

If the capability does not already exist on KnowledgeService:

1. Add the method to the KnowledgeService interface in src/services/types.ts, signature (input: XInput, ctx: RequestContext) => Promise<XResult>.
2. Add XResult to src/domain/types.ts.
3. Implement it inside createKnowledgeService() in src/services/knowledge-service.ts and add it to the returned object at the bottom of the factory.
4. Wrap every MongoDB call in guarded(logger, 'collection.operation', () => …) so a raw MongoServerError never escapes as an unclassified failure.

If the capability is already on the service (listDocuments, getDocument, reembed, embeddingCoverage all exist and are currently only reachable over REST), skip to step 2.

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Step 2 — Add the schemas to src/domain/schemas.ts

Three exports per tool, following the file's existing convention exactly:

// ---------------------------------------------------------------------------
// summarize_source
// ---------------------------------------------------------------------------

export const summarizeSourceShape = {
  sourceId: sourceIdSchema.describe('Source to summarise.'),
  maxChunks: z
    .number()
    .int()
    .min(1)
    .max(50)
    .default(10)
    .describe('How many leading chunks to include.'),
} satisfies z.ZodRawShape;

export const summarizeSourceSchema = z.object(summarizeSourceShape).superRefine(/* … */);
export type SummarizeSourceInput = z.infer<typeof summarizeSourceSchema>;

export const summarizeSourceOutputShape = {
  sourceId: z.string(),
  title: z.string(),
  chunkCount: z.number().int(),
  updatedAt: z.string(),
} satisfies z.ZodRawShape;