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Executable runtimes are not permitted on the Coral marketplace
Executable runtimes can be configured to run an executable of your choice. This is a useful development runtime, allowing you to run your agent without containerizing it first.

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Full example

[runtimes.executable]
path = "python3"
arguments = ["main.py"]
transport = "streamable_http" # default value

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Environment

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Standard streams

Timestamps and log levels are prefixed by the Coral server, the agent should not print these.
  • Standard output will be printed to the agent’s log at an INFO level.
  • Standard error will be printed to the agent’s log at a WARN level.
  • Standard input is not used

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Coral environment variables

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CORAL_CONNECTION_URL

The URL of the MCP server that this agent must connect to, either SSE or Streamable HTTP depending on the value given for runtimes..transport. This URL will change every time the agent is launched. This URL contains the agent secret and should not be printed or shared. The value of this should also not be given to an LLM.

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CORAL_RUNTIME_ID

Always set to .

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CORAL_AGENT_ID

The unique name provided for this agent in GraphAgentRequest.name.

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CORAL_AGENT_SECRET

A unique secret generated for this agent. This secret is used to authenticate communications between the agent and the Coral server. This secret should not be printed, shared or given to an LLM.

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CORAL_SESSION_ID

The unique ID of the session that this agent belongs to. This ID is generated by the Coral server and is used uniquely to identify a session. This ID should not be printed, shared or given to an LLM.

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CORAL_API_URL

The base URL of the Coral server. This can be used to RPC requests to the Coral server on behalf of the agent. All requests to the Coral server must be authenticated with the agent secret.

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Optional Coral environment variables

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CORAL_PROMPT_SYSTEM

If the session that launched this agent defines a systemPrompt, it will be set to this environment variable. If not, this variable will not be set.

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CORAL_REMOTE_AGENT

Placeholder. Currently not used.

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Other environment variables

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Configuration

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runtimes.executable.path

required Example 
[runtimes.executable]
path = "bootstrap"
Arguments cannot be provided in the path. All arguments must be provided via runtimes.executable.arguments
A string representing the path to the executable. This can be:
  • A name of an executable/script on your systems PATH environment variable
  • An executable, relative to the coral-agent.toml file
  • An absolute path to an executable/script
Requirements:
  • The executable path must be between 1 and 4096 characters long.
On Windows, the Coral server will try to append the extensions:
  • .exe
  • .cmd
  • .bat
To the executable path. If no files are found with these extensions, it will fallback to the specified path with no extension.This is a useful feature when developing an agent that requires a bootstrap script.Consider the following structure:
my-agent
src
...
coral-agent.toml
bootstrap
bootstrap.bat
The example will execute the bootstrap file (use a shebang in this file) on Unix and the bootstrap.bat on Windows.

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runtimes.executable.arguments

optional An array of strings denoting the arguments to pass to runtimes.executable.path Example 
[runtimes.executable]
path = "npm"
arguments = ["run", "start"]
Requirements:
  • No more than 1024 arguments can be provided.
  • The total size of all arguments must not exceed 2 KiB

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runtimes.executable.transport

default streamable_http
optional Example 
[runtimes.executable]
transport = "sse"
sse is deprecated and may be removed in a future release.
A string controlling the value of the CORAL_CONNECTION_URL Coral environment variable. If your agent requires a specific MCP transport protocol, it must be set here. Supported values:
  • sse
  • streamable_http