In 2026 every agent host loads its tools from a static config file. By 2027 the same hosts will discover tools the way browsers discover printers — dynamically, with capability negotiation and signed advertisements. Here are the three discovery approaches in flight, and which one to build against today.
Why static configs hit a wall
A team with 50 MCP servers across 200 developers needs every laptop's config kept in sync. The current solutions — ChatOps copy-paste, version-controlled configs, team config tooling — all paper over the underlying problem: configs are static and tools are dynamic.
Discovery solves the underlying problem. The host asks "what tools are available here?" instead of being told.
The three approaches
DNS-SD (RFC 6763)
Reuse mDNS / DNS-SD: tools advertise themselves on the network as _mcp._tcp services with TXT records describing capabilities. Hosts subscribe and discover everything visible on the network.
- Strengths: existing infra, zero new protocols, multicast on LAN works out of the box.
- Weaknesses: does not cross network boundaries; sparse capability metadata.
- Best for: corporate LANs, dev environments.
Well-known endpoints
A host fetches https://example.com/.well-known/mcp and gets back a JSON list of available servers with auth requirements and capability summaries.
- Strengths: works across the public internet; easy to secure (TLS + signed).
- Weaknesses: push model — hosts have to know to ask.
- Best for: SaaS providers exposing their own MCP servers; per-domain discovery.
mcp-discover (proposed)
A protocol-level extension to MCP itself: a discovery endpoint returns server descriptors, capabilities, signing fingerprints, and renewal hints. Standardisation in flight at the time of writing.
- Strengths: native to MCP; signed; fine-grained capability metadata.
- Weaknesses: not yet standardised; client support patchy.
- Best for: future-proof setups; bet on the standard once it lands.
Capability negotiation
Discovery alone is not enough. The host needs to know:
- Which tools the server exposes.
- Required permissions / scopes.
- Compatibility (MCP protocol version, transport).
- Signing fingerprint for verification.
A discovery descriptor:
{
"name": "internal-postgres",
"version": "1.4.0",
"protocol": "mcp/1.0",
"transport": "stdio",
"tools": ["query", "schema"],
"scopes_required": ["postgres:read"],
"signature": "ed25519:a8f3...",
"ttl_seconds": 3600
}
The host subscribes, validates the signature, checks compatibility, and only then offers the server to the agent.
Trust on top of discovery
Discovery without verification is worse than static configs — it surfaces every server an attacker can advertise. Three layers of trust:
- Signed descriptors — refuse unsigned advertisements.
- Anchored to a registry — only trust servers whose signing key is in your self-hosted registry.
- Scope enforcement at the gateway — even discovered servers must request scopes the user has.
Discovery surfaces options; trust layers decide what is allowed.
Migration path
Don't replace static configs overnight. Layer:
- Keep static configs for production-critical tools.
- Add discovery for dev-environment tools.
- As discovery proves out, move tools one at a time.
- Eventually static configs hold only the bootstrap (where to discover).
Most teams will live in a hybrid state for years.
What to build today
Bet on mcp-discover with a well-known endpoint fallback. DNS-SD is useful for LAN scenarios but not where most production agents live. Implementing the well-known endpoint today is a one-day job; the descriptor format is forward-compatible with the standard.
Failure modes
- Stale advertisements — TTL too long, server gone but still advertised.
- Capability misadvertising — server claims tools it does not implement.
- Discovery floods — too many servers; UI noise. Filter at the host.
- Spoofing — unsigned discovery is a phishing vector.
Where this is heading
Two shifts to expect by mid-2027: a finalised discovery protocol in MCP spec, and MCP-aware DNS extensions for cross-network discovery. Whoever builds the descriptor schema today will shape the standard.