MCP Config Reference
MCP Config Reference
Start with meaning, then move to detail.
This lesson explains MCP Config Reference as part of extending Hermes and connecting external tools. You will learn what it does, when it matters, and the smallest safe test that proves it works.
If you are new, do not memorize names. Focus on three questions: what problem does this solve, what access does it need, and how can you verify the result?
For practice, inspect the first example, identify its effects, run it on test data, and compare the result with the source claim.
For advanced readers, inspect Root config shape, Server keys, Environment variable references, then verify failure modes and version compatibility.
Complete installation and one successful task before adding new capabilities.
A clear outcome before you read.
- Understand MCP Config Reference without assumed prior knowledge.
- Separate the source description from what still needs testing in your environment.
- Read the first command and identify its inputs and outputs before copying it.
Short definitions before the details.
- MCP
- A standard way to expose external tools, resources, and services to an agent.
- Tool
- A structured action the agent can call to read or change something.
Reference for Hermes Agent MCP configuration keys, filtering semantics, and utility-tool policy
What does the source say, and in what order?
- 01Root config shape
Start here to understand the core idea or structure.
- 02Server keys
Read this after the foundation, then connect it to the previous step.
- 03Environment variable references
Read this after the foundation, then connect it to the previous step.
- 04Context variables
Read this after the foundation, then connect it to the previous step.
- 05tools policy keys
Read this after the foundation, then connect it to the previous step.
- 06Filtering semantics
Read this after the foundation, then connect it to the previous step.
- 07include
Read this after the foundation, then connect it to the previous step.
- 08exclude
Read this after the foundation, then connect it to the previous step.
- 09Precedence
Read this after the foundation, then connect it to the previous step.
- 10Utility-tool policy
Finish here to verify the result and special cases.
Copy only after you understand the effect.
mcp_servers:
<server_name>:
command: "..." # stdio servers
args: []
env: {}
# OR
url: "..." # HTTP servers
headers: {}
# Optional HTTP/SSE TLS settings:
ssl_verify: true # bool or path to a CA bundle (PEM)
client_cert: "/path/to/cert.pem" # mTLS client certificate (see below)
# client_key: "/path/to/key.pem" # optional, when key lives in a separate file
enabled: true
timeout: 120
connect_timeout: 60
supports_parallel_tool_calls: false
tools:
include: []
exclude: []
resources: true
mcp_servers:
github:
command: "npx"
args: ["-y", "@modelcontextprotocol/server-github"]
env:
GITHUB_PERSONAL_ACCESS_TOKEN: "${env:GITHUB_TOKEN}" # same as "${GITHUB_TOKEN}"mcp_servers:
filesystem:
command: "npx"
args: ["-y", "@modelcontextprotocol/server-filesystem", "${workspaceFolder}"]
env:
CACHE_DIR: "${userHome}${/}.cache${/}mcp"Read the first command and identify its inputs and outputs before copying it.
Match every command to your installed Hermes version, review the files and accounts it can reach, and use non-sensitive data for the first test. If this explanation differs from the source, the official source wins.