Activity kinds reference

Full API templates and rules for all five activity kinds — cli, mcp_tool, code, llm, and builtin.

`cli`

Runs a shell command or external binary.

Template:

steps/NN_name.ts

import { step } from '@cori-do/sdk';
import { z } from 'zod';

export const input = z.object({
  // define step inputs
});

export const output = z.object({
  // define step outputs
});

export default step.cli({
  description: 'What this step does',
  command: ({ input }) => `your-binary --flag ${input.some_value}`,
  parse_output: (stdout) => ({
    // parse stdout into output shape
  }),
});

Rules:

Declare the binary in the manifest's tools_required. Validated at cori check time.
If the binary is not found on PATH, run cori status to check the worker's environment.
Default retry: 1 attempt (transient failures are not automatically retried).
Default per-attempt timeout: 60 seconds.

`mcp_tool`

Calls a tool on an MCP server.

Template:

steps/NN_name.ts

import { step } from '@cori-do/sdk';
import { z } from 'zod';

export const input = z.object({
  // define step inputs
});

export const output = z.object({
  // define step outputs
});

export default step.mcp_tool({
  description: 'What this step does',
  server: 'server-name',   // must match mcp_servers in manifest
  tool: 'tool_name',
  args: ({ input }) => ({
    // tool arguments
  }),
  parse_output: (result) => ({
    // parse MCP result into output shape
  }),
});

Rules:

Declare the MCP server in the manifest's mcp_servers. Validated at cori check time.
Default retry: 1 attempt.
Default per-attempt timeout: 60 seconds.

`code`

Pure TypeScript computation with no I/O.

Template:

steps/NN_name.ts

import { step } from '@cori-do/sdk';
import { z } from 'zod';

export const input = z.object({
  // define step inputs
});

export const output = z.object({
  // define step outputs
});

export default step.code({
  description: 'What this step does',
  run: ({ input }) => {
    // pure computation — no network, no filesystem, no shell
    return {
      // output shape
    };
  },
});

Rules:

Never put external I/O in a code step. No network calls, no filesystem reads, no shell commands. Code steps run in the Temporal workflow execution context and must be deterministic pure functions.

Default retry: 3 attempts.
Default per-attempt timeout: 30 seconds.

`llm`

Calls a language model with a prompt and parses the typed output.

Template:

steps/NN_name.ts

import { step } from '@cori-do/sdk';
import { z } from 'zod';

export const input = z.object({
  // define step inputs
});

export const output = z.object({
  // define step outputs — required for llm steps
});

export default step.llm({
  description: 'What this step does',
  model: 'gpt-4o-mini',
  prompt: ({ input }) => `Your prompt here. Data: ${JSON.stringify(input)}`,
  output_schema: output,
  // optional:
  system: 'You are a helpful assistant.',
});

Rules:

output_schema is required. LLM steps must declare a typed output.
Use llm only for content that varies at runtime (translation, classification, extraction).
Provider credentials are configured at the worker level, not in the step file.
Default retry: 3 attempts.
Default per-attempt timeout: 300 seconds.

builtin steps are accepted by the compiler but the v1 runtime does not execute them. The constructors below are documented for reference only. Do not use them in workflows you intend to run today.

The builtin constructors provide workflow-level control flow:

Constructor	Description
`step.builtin.map(...)`	Fan out over a list, run a step per item
`step.builtin.for_each(...)`	Iterate over items sequentially
`step.builtin.branch(...)`	Conditional execution
`step.builtin.parallel(...)`	Run multiple steps concurrently
`step.builtin.wait(...)`	Wait for an external event or signal

These will be executable in a future version of Cori.

Activity kinds reference

`cli`

`mcp_tool`

`code`

`llm`

`builtin` — deferred in v1

On this page

Activity kinds reference

cli

mcp_tool

code

llm

builtin — deferred in v1

On this page

`cli`

`mcp_tool`

`code`

`llm`

`builtin` — deferred in v1