Input and Output Contracts

Input and output contracts are validation and interpretation hints. They do not replace the native protocol schema.

Input contract

tool_input_contract SHOULD include:

• JSON Schema-compatible model_input_schema.
• Optional runtime_input_schema for internal fields.
• strict when the provider/runtime can enforce schemas.
• defaults where safe.
• examples for model grounding.
• sensitive_fields for redaction and telemetry controls.
• internal_only_fields that must not be model-generated.
• argument_mode: json, text, file, multipart, stream, or custom.
• mutation_policy: whether hooks or permission prompts may replace input.

Input variants

Keep these separate: model_input, observable_input, permission_input, and call_input. This prevents path normalization, permission UI edits, or internal fields from corrupting the original model-provided arguments.

Output contract

tool_output_contract SHOULD include:

• structured_schema for structured content.
• content_types for text, image, audio, video, file, log, or resource refs.
• artifact_expectations when the tool should produce a durable deliverable.
• max_inline_bytes or max_inline_chars to prevent giant payloads entering prompts.
• persistence_policy_ref for preview, persist, redaction, and never-persist rules.
• rendering_boundary to separate model content, UI rendering, and transcript search text.
• redaction_rules and fallback_summary guidance.

If a native protocol already has schemas, Agent Tool should reference them and add agent-specific interpretation rather than copying everything.