Move the Prompt Tools API Into Your Own Scripts Before Workbench Closes on August 17
The legacy Workbench and three experimental prompt endpoints shut down on August 17, 2026. Here is how to count what actually depends on them, plus working local replacements for templatize_prompt and improve_prompt with real output.
Swapping Tools Mid-Conversation Without Losing Your Prompt Cache
Tools can now be added and removed between turns, but the tool block sits at the very front of the cache prefix. I measured 12 mutation patterns with fingerprints and built a stable-core plus volatile-tail registry with a guard that refuses unsafe changes.
Full-Size or Downscaled? A Per-Image Resolution Rule for Opus 4.7's High-Resolution Vision
Opus 4.7 finally read the fine texture in my wallpapers, so I sent everything at full size. My weekly image tokens jumped 2.4x. Here is the preflight that decides resolution and model per image, with the measured savings.
Designing Around Claude API 413 request too large — Preflight Sizing and Splitting
Pack too much text, images, and tool_result into one request and Claude API rejects it with 413 request too large. Here is a code-backed design for measuring request bytes before you send, telling the two kinds of 413 apart, and splitting requests without breaking them.
When You Give an API Key an Expiration Date, Expiry Becomes a Plan Instead of an Accident
The Console now lets you set expiration dates on API keys. Here is how to fold planned expiry into unattended operations — with overlapping dual keys and a local expiry ledger — so your nightly jobs never go dark.
Tightening Tool Schemas From the Arguments You See in Production
Record the arguments Claude actually passes to your tools in production, then use that distribution to add enums and patterns back into your JSON Schema. With logging code and before/after numbers.
When Whisper Wrote 'Thanks for Watching' Into the Silence — Measuring and Killing Japanese Transcription Hallucinations
Whisper inserts phantom boilerplate into silent or noisy segments of Japanese audio. Here is how to measure hallucinations with no_speech_prob and avg_logprob, strip silence with VAD, and have Claude validate what remains — with the implementation and the routine that pulled it back.
Don't Trust the Confidence Score: Per-Class Calibration and Abstain Routing for Vision Classification
Overall accuracy looked fine while individual categories quietly collapsed. Here is how I calibrated Claude Vision's self-reported confidence per class and routed abstentions to a human queue.
My Nightly Batch Was Quietly Running on a Bigger Model — Declaring Per-Task Model Ceilings and Enforcing Them
Scatter model names through your code and a cheap batch job will eventually run on an expensive model. Here is a manifest that declares a ceiling per task, a deny-by-default resolver, and a morning audit that catches drift — with working code.
When the RAG Started Being Confidently Wrong — Field Notes on Measuring Retrieval Misses With Groundedness
In a Claude API RAG, the answers stay fluent while the facts drift. Often the cause is a silent recall decay on the retrieval side, missing the document that holds the answer. Field notes on measuring groundedness and retrieval hit rate and walking the system back, with working code and real numbers.
Contract-Test Every Tool Before You Submit or Automate an MCP Connector
A connector that works once in a chat can still break silently in an unattended job through misread response shapes or double-fired writes. Here is a small harness that machine-checks tool descriptions, response contracts, idempotency, and latency, with measured numbers.
Four sites, one Claude bill: attributing spend per workspace to decide which pipeline to trim
When several projects share one Claude organization, the bill arrives as a single number that hides which pipeline is expensive. Field notes on splitting that spend per workspace with the Cost and Usage Report group_by, defensively parsing the results, and deciding what to trim by cost-effectiveness.