Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add ElemontCapital/x-algorithm-skills --skill x-retrieval-systemsgit clone --depth 1 https://github.com/ElemontCapital/x-algorithm-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/elemontcapital/x-algorithm-skills/x-retrieval-systems)<a href="https://agentmods.dev/skills/elemontcapital/x-algorithm-skills/x-retrieval-systems"><img src="https://agentmods.dev/badge/skills/elemontcapital/x-algorithm-skills/x-retrieval-systems/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/elemontcapital/x-algorithm-skills/x-retrieval-systems"><img src="https://agentmods.dev/badge/skills/elemontcapital/x-algorithm-skills/x-retrieval-systems.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00053 | $0.00379 |
| Opus 5 | $0.00026 | $0.00189 |
| Sonnet 5 | $0.00011 | $0.00076 |
| Haiku 4.5 | $0.00005 | $0.00038 |
Grade A, and why
x-retrieval-systems scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
X Retrieval Systems
Expertise in X's multi-stage retrieval architecture, including Earlybird search indexing and Phoenix-based ANN similarity search.
Context
Retrieval at X is split between In-Network (content from people you follow) and Out-of-Network (discovery). In-Network retrieval relies on Earlybird (Lucene-based search), while Out-of-Network retrieval uses Phoenix (Two-Tower embeddings) and ANN (Approximate Nearest Neighbor) algorithms like HNSW.
What it does
- Decodes In-Network Sourcing: Explains how Earlybird shards the index into Realtime, Protected, and Archive clusters.
- Explains Discovery Logic: Details how Two-Tower models enable "semantic" search for content you don't follow.
- Analyzes Latency: Breaks down the single-writer/multi-reader concurrency model that allows for sub-second global retrieval.
Example Trigger Prompts
- "/find-candidates how Earlybird shards real-time index"
- "/find-candidates retrieving 1,500 candidates from 500M tweets"
- "Role of HNSW in embedding-based discovery"
- "In-Network (Thunder) vs Out-of-Network (Phoenix) retrieval"
- "Trace 'Discovery' request: User Embedding → Candidate Source"
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 9d ago First seen · 31 lines · 53 tokens per session scan A dc1caac580e8
x-retrieval-systems is a skill published in the GitHub repository ElemontCapital/x-algorithm-skills (2 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 53 tokens to every session and 379 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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