Tool contracts and errors

Tool contracts and error shapes

• A Tool Contract for Failure: Inputs, Outputs and Error Codes
• Error Envelopes Across Tool Types: HTTP, Database, APIs
• Schema Tests for Tools: Fixtures That Assert Every Error Code
• The Envelope's Version Field: Adding a Class Safely
• A First-Key Contract for an Internal API Between Two Teams
• A Reason Code Namespace Behind the Envelope Version
• A Subscriber Manifest: Which Services Depend on Which Fields
• Contract Tests Between an Agent and Its Tool Schema
• All of Tool contracts and errors

Tool gateways

Tool gateways and schema enforcement

• A Tool Gateway That Refuses on Tier, Not on Argument
• What a Gateway Should Assert Before Forwarding a Model Reply
• A Schema Hash Is a Release Artifact: Versioning It
• Audit Queries for Tool Access: Caller, Tier and Approval
• Countable Failures: A Log Schema for Tool Result Gates
• Prompt, Validator or Gateway: Where a Rule Lives
• Validating Agent Tool Calls Before Execution
• What an LLM Gateway Should Log and Keep

Tool errors and retries

Tool errors and retry recovery

• Classifying Tool Errors So an Agent Can Act on Them
• Retry Prompts That Quote the Failing Tool Call Back to the Model
• Tool Error Recovery: Structuring Failures for Retries
• A Queue Owner Table per Error Class: Who Gets the Escalation
• A Retry-After Field: Passing Backoff Hints From Tool to Agent
• A Token Budget for the Retry Turn
• Classifying Tool Errors by Whether a Retry Can Fix Them
• Measuring Repair Success Rate per Error Class
• All of Tool errors and retries

Streaming and server-sent events

Server-sent events and streaming tools

• A Streaming UI State Machine: Close, Partial and Error States
• Streaming Structured Output: Handling Partial JSON
• A Field-Order Test for Server-Sent Events Frames
• Reordering a Response Schema Without Breaking a Streaming Parser
• Saving Partial Streamed Output: Staging Rows and Commit Rules
• Server-Sent Events vs WebSockets for Token Streams
• Streaming Tool Calls: Parsing Arguments Before the Call Ends
• What a Stream Log Must Record to Replay a Failed Render