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CHP vs MCP tools

MCP tools center model-callable tool access. CHP centers independent hosted capability boundaries for agents, apps, products, and infrastructure.

Plain English

CHP is not a replacement for model tool protocols; it defines the host-side contract around governed capabilities.

Why it exists

Agent tool schemas do not by themselves standardize lifecycle, permission, version compatibility, structured denials, evidence, replay, or conformance.

Formal definition

CHP is a public capability-host protocol that can be called by agents and frameworks while preserving host identity, policy state, outcome semantics, and evidence.

Concrete example

Ground the concept before the schema.

An MCP tool can call schedule_technician through CHP instead of encoding dispatch policy and evidence in tool glue.

schedule_technicianInvokable

Finds an available qualified technician and reserves a service window.

host: ServiceOpsHostpolicy: approval_requiredv1.0.0

Policy boundary

Approval required

manager_approval

A manager must approve technician scheduling before the host returns a confirmed appointment.

Invocation trace

  1. 01 Actor

    Planning Agent

  2. 02 Capability

    schedule_technician

  3. 03 Host

    ServiceOpsHost

  4. 04 Policy

    manager_approval

  5. 05 Context

    job_context

  6. 06 Result

    Confirmed Appointment

Category contrast

CHP vs MCP tools: what changes

CHP can complement adjacent systems, but it centers a different protocol boundary.

Compared to

MCP tools

They center

Model-callable tool descriptions and tool invocation from agent clients.

CHP centers

Host identity, capability lifecycle, policy, structured outcomes, evidence, replay, and conformance.

Use MCP where the agent client needs a tool interface.

Use CHP where the capability host needs a portable public protocol boundary.

Use both when an agent tool invokes an independently governed capability host.

Relationships

Where this sits in the protocol.

Each concept should explain its neighbors so implementation teams can preserve the boundary across manifests, invocation, evidence, and tests.

MCP can be a caller-facing integration surface.

CHP defines host-side capability semantics.

Adapters can bridge tool ecosystems into CHP hosts.

Visual model

  1. 01Agent framework selects a tool.
  2. 02Tool invokes a CHP capability host.
  3. 03Host enforces lifecycle, policy, and evidence.

Implementation notes

  • Keep model tool schemas aligned with CHP manifest metadata.
  • Return CHP denials to the agent as structured information.
  • Do not put host credentials or policy decisions in prompt glue.

Common mistakes

  • Treating a tool schema as the full operational contract.
  • Skipping replayable evidence for agent actions.
  • Letting every framework invent different denial semantics.

Related concepts

Keep reading through the boundary.

Host →Policy →Evidence →