MCP Contracts And Navigation

Use this page when an MCP client or agent needs the machine-readable runtime contract rather than prose examples.

Discovery Order

  1. Start the server with the target policy gates needed for the task.
  2. Call MCP discovery such as initialize, tools/list, prompts/list, and resources/list.
  3. Read wpf://contracts/tools for tool names, categories, parameters, required fields, reflection-backed parameter constraints, capability tags, and policy tags.
  4. Read wpf://contracts/response for response envelopes, compatibility aliases, navigation metadata, and error recovery fields.
  5. Read wpf://capabilities when the client needs a compact capability summary.

Do not hard-code tool arguments from old screenshots or prior runs. Runtime discovery is the source of truth.

Each manifest parameter may include a compact constraints object. Fields such as minLength, maxLength, minimum, and maximum mirror the validation annotations that also contribute to inputSchemaHash; use them when a client cannot expose the raw tools/list input schema.

Prompt And Resource Names

Some clients render MCP prompts and resources with client-specific shortcuts. Treat the standard names and URIs as the portable contract:

Surface Portable name
Binding triage prompt debug_binding_issue
Capability resource wpf://capabilities
Tool contract resource wpf://contracts/tools
Response contract resource wpf://contracts/response

If a client displays a shortcut such as /mcp__wpf-devtools__debug_binding_issue, keep the underlying prompt name in notes and automation.

Response Fields To Prefer

Structured clients should treat result.structuredContent as canonical. Use result.content[0].text as a compact fallback for clients that cannot render structured payloads.

When present, follow navigation.recommended before improvising the next call. Use navigation.alternatives for human-guided branches, prefetchTools for progressive schema loading, and contextRefs as descriptive context only. contextRefs are not executable handles.

nextSteps remains the compatibility field for older clients and is usually derived from navigation.recommended.

get_binding_errors advertises navigation=false in its runtime schema. Agents may use it when the next action is already obvious and token volume matters.

Do not pass navigation=false to other tools unless their tools/list schema advertises the parameter.