Reference
MCP contract glossary
The vocabulary this product uses, defined precisely. Every term links to itself, cite them.
Tool schema
The JSON Schema an MCP server advertises for a tool's inputs (and optionally outputs). Part of the contract, alongside the tool's name and description.
Snapshot
The canonical, content-hashed form of a server's full advertised contract at a point in time: tools, resources, prompts. Immutable; identical contracts hash identically regardless of key order.
Manifest
A generated declaration of what one agent actually uses: which tools it calls and which fields it sends and reads, with call sites. The basis for blast radius and CI checks.
Pin
The snapshot hash a manifest declares as its target contract. Accepting a new contract points every affected manifest at the new schema, so CI fails until your call sites match, it means 'fix in progress', never 'resolved'. Unlike an npm lockfile a pin cannot hold the server back; the upstream schema has already shipped.
Blast radius
The per-consumer impact of a change: which agents are affected, by which fields, at which call sites. Computed by crossing a classified diff with manifests.
Breaking / risky / safe
Consumer-perspective severity classes. Breaking: existing valid requests become invalid or read fields disappear. Risky: nothing errors but behavior may shift (including large description rewrites). Safe: cosmetic.
Contract check
CI verification that a manifest still satisfies its pinned snapshot. Exits nonzero on drift from either side. A green check is the only thing that resolves an incident.
Exposure window
Minutes between a break being detected and the fix being verified by CI. The number an engineering lead actually cares about.
Advisory
A published record of a breaking change observed on a public server (ZV-YYYY-NNNN), like a CVE for contract breaks.
Description drift
Changes to a tool's description text. Invisible to conventional API diffing, but model-facing text steers tool selection and argument construction, so it's contract surface.