Traditional RAG is a fixed pipeline of 'retrieve then answer.' Agentic RAG splits retrieval into three decision layers: when to retrieve (FLARE uses token probabilities; Adaptive-RAG uses a complexity classifier), what to retrieve (HyDE / RAG-Fusion / decomposition / Step-back), and how to fuse (RRF k=60 then cross-encoder rerank then compression -- Anthropic measured a -67% failure rate reduction). Key counter-intuitive insight: unnecessary retrieval hurts quality -- 'deciding not to retrieve' is a first-class capability.
Automatic prompt optimization (APO) has evolved from APE/OPRO to GEPA: replacing sparse rewards with linguistic reflection, winning over GRPO by ~6pp with 4-35x fewer rollouts. Meanwhile, tool descriptions are the overlooked prompt -- small wording changes can shift tool selection rates by 10x, and Anthropic's experiments show Claude self-rewriting tool descriptions outperforms human experts. These two lines are converging: eval-driven automatic optimization is eating hand-tuned prompts.
Inferring another's beliefs/goals/intentions from observed behavior is called Machine Theory of Mind. Three lineages: symbolic BDI, Bayesian inverse planning, and deep learning ToMnet. The biggest controversy in the LLM era is that GPT-4 still trails humans by >10 points on ToMBench — are high scores genuine reasoning or statistical shortcuts?
At 99% accuracy per step over 100 steps, the error-free completion rate drops to just 36% -- error compounding is a structural problem, not something prompt tuning can fix. Distributed systems' supervisor trees, bulkheads, circuit breakers, sagas, and durable execution can be mapped almost one-to-one into agent orchestration. But LLMs introduce a failure class that traditional systems never had -- semantic errors that don't crash -- which require Inspector agents (recovering 96.4%) and redundancy voting (MAKER: one million steps with zero errors) to address.
Cosine similarity and relevance systematically diverge across an entire class of scenarios: negation (most IR models score at or below random on NevIR), exact identifiers, numeric thresholds, and logical combinations (SoTA models achieve recall@100 < 20 on LIMIT) -- some of these hit the theoretical ceiling of the single-vector paradigm, and switching to a larger model will not help. Recommended remedy order: hybrid BM25 -> reranker (Anthropic measured -67%) -> upstream metadata routing -> domain fine-tuning / multi-vector.
As tools scale up, selection accuracy doesn't degrade gracefully — it collapses: 4 to 51 tools drops from 43% to 2%, 10 to 100+ drops from 78% to 13.62%. The root fix is to stop stuffing everything in at once — Anthropic's Tool Search Tool uses defer loading plus retrieval to cut 85% of tokens, pushing Opus 4.5 accuracy from 79.5% to 88.1%. Description quality has conditional payoff: negligible in simple scenarios, but correctness jumps from 44% to 50% in multi-tool chaining.
Traditional Chinese RAG retrieval failures are a three-layer stack: embedding granularity defects (BGE/GTE from 0.1B to 7B all mis-rank on simple queries like 'fried chicken'), Simplified Chinese / English corpus dominance causing local vocabulary drift ('premium', 'exclusion clause' alignment is unreliable), and MTEB Chinese benchmarks being Simplified Chinese making model selection signals misleading. The fix is architectural: OpenCC normalization -> hybrid + jieba segmentation -> reranker -> local fine-tuning last -- and the prerequisite for all of it is building a Traditional Chinese eval set first.
arXiv does not perform peer review, and roughly 2% of submissions are rejected. Quality judgment relies on external signals: top venue acceptance > institution + open-source reproduction > citation quality. Includes a 20-item practical checklist and a 2026 toolbox (PWC has shut down).
Making 'chunk and embed every uploaded file automatically' the default behavior means making a decision for the LLM that it could have made itself. From Self-RAG (2310.11511) and Adaptive-RAG (2403.14403) to AgenticOCR (2602.24134), the academic trajectory is pushing three layers of decision-making -- whether to retrieve, whether to parse, and how to chunk -- from the ingestion pipeline back to the agent at conversation time.
The hard part of LLM agents is not building function calling, skills, code interpreter, and document tools individually -- it is assembling them into a system that selects the right tool, writes code when needed, decomposes tasks, verifies results, and resists prompt injection. This post organizes the key papers into six engineering decisions: function calling reliability, tool/skill selection, code-as-action, multi-step planning, skill systems, and safety plus document generation.
A2UI is an agent generative UI protocol open-sourced by Google on 2025-12-15: agents send declarative JSON describing UI intent, and clients render it natively using their own component catalog whitelist, layered on top of A2A. It launched at format v0.8 and iterated to v0.9 within three months.
browse.sh, launched by Browserbase in May 2026, is two things: a browser skill catalog and the Browse CLI. The core thesis: the bottleneck for browser agents isn't reasoning — it's amnesia. By storing learned site-specific workflows as plain-text SKILL.md files, Autobrowse cut Craigslist task costs from ~$0.22 to ~$0.12 by their own metrics. Note: this has nothing to do with the 2018 Browsh text-mode browser.
CodeGraph uses tree-sitter to extract a codebase into a local SQLite/FTS5 knowledge graph, letting AI coding agents query the graph instead of scanning files. The official end-to-end benchmark (7 repos, median of 4 runs) averages 35% cost savings and 70% fewer tool calls -- but only if the agent actually walks the graph. Delegating exploration to a file-reading subagent that ignores CodeGraph turns it into pure overhead.
Reading papers is two problems stacked together: methodology (Keshav's three-pass method, 5-10 min / 1 hour / 4-5 hours) determines how to read, and tools (arXiv HTML, alphaXiv, NotebookLM, Connected Papers, Zotero) shorten the time for each pass. AI lowers the barrier to understanding; judging correctness always stays with the human.
An MIT-licensed open-source UI automation framework from ByteDance. UI actions rely solely on feeding screenshots to a vision-language model, with no DOM parsing. A single JS API works across Web / Android / iOS / desktop. The trade-offs: each step is slower and more token-expensive, and everything hinges on the model's grounding ability. Note that Midscene retired MCP after 1.9.8 in favour of Skills + CLI.
Claude has no docx_tool or pdf_tool -- it relies on bash + file tools, plus SKILL.md instructions and pre-installed libraries like pdfplumber / python-pptx inside the container, assembling file handling capabilities from three layers.
Anthropic shipped Claude Design on 2026-04-17. On 4-28, nexu-io/open-design went public -- same artifact-first loop, Apache-2.0, runs on the 16 coding-agent CLIs you already have. Two weeks from 0.1 to 0.7, 40k+ stars. A paradigm shift that flattens AI design tools from vertical SaaS into a skill bundle.
asgeirtj/system_prompts_leaks collects the raw system prompts of 40+ AI assistants, from GPT-5.5 and Claude Opus 4.7 to Gemini 3.1 Pro, with 40.3k stars, 461 commits, and an MIT license. The value isn't in obtaining secrets -- it's in turning vendors' implicit policies into comparable engineering material. What you should study is the design decisions, not the text itself.
Anthropic's 35-page startup handbook released 2026-05-14 reorganizes Idea/MVP/Launch/Scale around agentic AI. The most valuable takeaways are 'the easier it is to build, the more important validation becomes' and treating CLAUDE.md as the first MVP artifact. The part to discount: the Launch chapter puts compliance workstreams on Cowork -- but Anthropic's own docs say Cowork doesn't write audit logs.