> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/harness-ai/use-harness-ai/core-capabilities/in-your-pipelines/worker-agent/harness-agents-references.md).
# Harness Agents reference
Harness Agents Reference
Worker Agent definitions use `agent.uses` to select a versioned template, `agent.with` to configure it, and `agent.inputs` to declare reusable parameters. The Harness-managed template supplies the container and runtime configuration.
## Worker Agent form field reference
The following fields define a Worker Agent. Required fields are marked in the **Required** column.
| Field | Required | Description | Example |
| ------------------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------- |
| **Name** | Yes | Human-readable identifier displayed in the catalog and pipeline step picker. | `PR Reviewer Agent` |
| **Description** | No | Free-text summary of what the agent does. Helps teams discover and reuse agents from the catalog. | `Reviews PRs for security, schema, and architectural issues.` |
| **Instructions** | Yes | The system prompt sent to the model at runtime. Supports Harness variable expressions for dynamic context injection. Go to [Configure instructions and Harness expressions](/harness-ai/use-harness-ai/core-capabilities/in-your-pipelines/worker-agent/configuration.md#configure-instructions-and-harness-expressions) to review dynamic context injection. | Example below |
| **Model Connector** | Yes | The LLM provider connector. When you configure the connector, you select a default model. Go to [Configure Model Connectors](/harness-ai/use-harness-ai/core-capabilities/in-your-pipelines/worker-agent/configuration.md#configure-model-connectors) for supported providers and models. | `anthropic_bedrock_99cf4be5` |
| **Model Name** | No | Optional override for the model used at runtime. If not specified, the agent uses the model on the Model Connector. If that model is also unset, Harness uses a provider default. Go to [Configure Model Connectors](/harness-ai/use-harness-ai/core-capabilities/in-your-pipelines/worker-agent/configuration.md#configure-model-connectors). Accepts an AWS Bedrock inference profile ARN for Anthropic connectors. | `arn:aws:bedrock:us-east-1:123456789012:application-inference-profile/a1b2c3d4e5f6` |
| **MCP Connectors** | No | One or more MCP server connectors granting the agent access to Harness platform data and external services (such as GitHub), or a local MCP server that runs inside the agent's container. Go to [Configure MCP connectors](/harness-ai/use-harness-ai/core-capabilities/in-your-pipelines/worker-agent/configuration.md#configure-mcp-connectors) for remote and local setup. | `harness_hosted_mcp` |
| **Inputs** | No | Named parameters declared under `agent.inputs` and referenced in the prompt with `<+inputs.inputName>`. | `projectName`, `orgId`, `repoName` |
| **Environment variables** | No | String values supplied to the runtime through `agent.with.env`. | `demo: "true"` |
| **Allowed domains** | No | Hostnames or regex patterns for domains the agent can reach. Harness domains are allowed by default. | `harness.io` |
***
## Agent definition YAML reference
The following YAML shows a Worker Agent definition in the **YAML** tab of the Worker Agent Catalog. Replace `harness_hosted_mcp` with your MCP connector identifier, and set the project and organization identifiers for your environment. Input names are case-sensitive: `projectName` must be referenced as `<+inputs.projectName>`.
```yaml
agent:
uses: harnessAI@1.0.0
with:
prompt: |
Analyze the pipelines in project <+inputs.projectName> in organization <+inputs.orgId>.
Use Harness MCP to list the pipelines and retrieve each complete pipeline YAML.
Identify repeated patterns and recommend improvements.
Write the complete analysis to pipeline_analysis_report.md in the working directory.
Confirm that the file exists and report its path.
When you finish, output a variable TASK_SUCCESS with value true if the
analysis succeeded, or false if it failed.
connector: account.harnessAnthropic
mcp:
- harness_hosted_mcp
allowed_domains: harness.io
env:
demo: "true"
swarm: "true"
inputs:
projectName:
type: string
required: true
default: Unscripted_Tour
orgId:
type: string
required: true
default: default
```
### YAML field reference
| Field | Description |
| ----------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `agent.uses` | Versioned base template. Use `harnessAI@1.0.0` for the Harness AI agent runtime. |
| `agent.with.prompt` | Agent instructions. Use a YAML block scalar (\` |
| `agent.with.connector` | Model connector identifier, such as `account.harnessAnthropic`. The connector supplies the default model and credentials. |
| `agent.with.mcp` | Optional list of MCP connector identifiers. Harness resolves their server configuration. |
| `agent.with.allowed_domains` | Optional comma-separated string of hostnames or regex patterns for domains the agent can reach over the network. Harness domains are allowed by default. |
| `agent.with.env` | Optional map of environment variable names to string values. Quote boolean-like strings such as `"true"`. Values can reference agent inputs or Harness secrets. |
| `agent.with.max_turns` | Optional limit on agent iterations. Supply a string, such as `"40"`. |
| `agent.with.output` | Not required for named pipeline variables. Tell the agent in **Instructions** which variables to output. Do not use this field to declare output variables. |
| `agent.with.workdir` | Optional working directory. Defaults to `/harness`. |
| `agent.with.backend` | Optional runtime backend. For the OpenAI-compatible LiteLLM setup, set `openai`. |
| `agent.with.image` | Optional custom agent container image. |
| `agent.with.docker_connector` | Optional Docker connector used to pull the agent image. |
| `agent.inputs` | Typed parameters referenced by the agent configuration. Each input has a `type` and can specify `required` and `default`. |
Go to [OpenAI Model Connector](/harness-ai/use-harness-ai/connect-with-ai/openai-model-connector.md#use-the-litellm-connector-in-a-worker-agent) to configure the LiteLLM backend.
{% @harness-feedback/feedback module="harness-ai" pagePath="harness-ai/use-harness-ai/core-capabilities/in-your-pipelines/worker-agent/harness-agents-references" %}