AgentFinger

AgentFinger
Developer	secondtruthLabs
Status	Draft
First published	2025
Latest version	0.3
Based on	CTRP
Transport	TCP
Default port(s)	7922 (TCP), 7923 (TLS)
Encoding	UTF-8
License	Public Domain

AgentFinger is an application protocol for discovering and retrieving structured information about users, AI agents, organizations, and MCP servers. Built on CTRP, it is specifically optimized for consumption by Large Language Models.

Overview

AgentFinger extends the classic Finger protocol concept for the AI agent ecosystem. It provides a standardized way for agents to discover information about other agents, their capabilities, and their organizational context.

Design philosophy

• Agent-first design – Optimized for LLM consumption
• Markdown-native – Semantic readability without complex parsing
• Distributed architecture – No central registry required
• Reasonable security – Designed for trusted networks

Technical specification

Entity types

AgentFinger supports four entity types:

Type	Prefix	Description
User	user:	Human users and their profiles
Organization	org:	Organizations and projects
Agent	agent:	AI agents and their capabilities
MCP Server	mcp:	MCP server capabilities

Query format

Queries follow a URI-like structure:

Query format

{{{code}}}

Examples:

Example queries

{{{code}}}

Type prefixes are mandatory to avoid ambiguity.

Response format

Responses use Markdown with YAML frontmatter:

Example response

{{{code}}}

Path-based resources

Entities can expose hierarchical resources:

Path examples

{{{code}}}

Query parameters

Parameter	Values	Description
format	md, json, yaml	Response format
section	Section name	Return only specified section

Security considerations

AgentFinger is designed for trusted network environments. Implementations should consider:

• Access control lists for sensitive information
• Rate limiting to prevent abuse
• TLS encryption for sensitive data
• Authentication for write operations (if supported)

Discovery

AgentFinger services can be discovered using TSDP:

TSDP discovery

{{{code}}}

Implementations

Reference implementation

The reference server implementation is written in Go.

Use cases

• Agent-to-agent communication and discovery
• Identity and context discovery for LLM personalization
• Organization and project documentation
• MCP server capability advertisement

See also

• Common Text-based Response Protocol
• Trivial Service Discovery Protocol
• wp:Model_Context_Protocol
• wp:Finger protocol

External links

• AgentFinger Repository