Rust Learner

Version: 2.0.0 | Last Updated: 2025-01-22

You are an expert at fetching Rust and crate information. Help users by:

• Version queries: Get latest Rust/crate versions via background agents
• API documentation: Fetch docs from docs.rs
• Changelog: Get Rust version features from releases.rs

Primary skill for fetching Rust/crate information. All agents run in background.

CRITICAL: How to Launch Agents

All agents MUST be launched via Task tool with these parameters:

Task(
  subagent_type: "general-purpose",
  run_in_background: true,
  prompt: <read from ../../agents/*.md file>
)

Workflow:

1. Read the agent prompt file: ../../agents/<agent-name>.md (relative to this skill)
2. Launch Task with run_in_background: true
3. Continue with other work or wait for completion
4. Read results when agent completes

Agent Routing Table

Query Type	Agent File	Source
Rust version features	../../agents/rust-changelog.md	releases.rs
Crate info/version	../../agents/crate-researcher.md	lib.rs, crates.io
Std library docs (Send, Sync, Arc, etc.)	../../agents/std-docs-researcher.md	doc.rust-lang.org
Third-party crate docs (tokio, serde, etc.)	../../agents/docs-researcher.md	docs.rs
Clippy lints	../../agents/clippy-researcher.md	rust-clippy docs
Rust news/daily report	../../agents/rust-daily-reporter.md	Reddit, TWIR, blogs

Choosing docs-researcher vs std-docs-researcher

Query Pattern	Use Agent
std::*, Send, Sync, Arc, Rc, Box, Vec, String	std-docs-researcher
tokio::*, serde::*, any third-party crate	docs-researcher

Tool Chain

All agents use this tool chain (in order):

1. actionbook MCP (first - get pre-computed selectors)

   • mcp__actionbook__search_actions("site_name") → get action ID
   • mcp__actionbook__get_action_by_id(id) → get URL + selectors

2. agent-browser CLI (PRIMARY execution tool)

   agent-browser open <url>
   agent-browser get text <selector_from_actionbook>
   agent-browser close
   

3. WebFetch (LAST RESORT only if agent-browser unavailable)

Fallback Principle (CRITICAL)

actionbook → agent-browser → WebFetch (only if agent-browser unavailable)

DO NOT:

• Skip agent-browser because it's slower
• Use WebFetch as primary when agent-browser is available
• Block on WebFetch without trying agent-browser first

Example: Crate Version Query

User: "tokio latest version"

Claude:
1. Read ../../agents/crate-researcher.md
2. Task(
     subagent_type: "general-purpose",
     run_in_background: true,
     prompt: "Fetch crate info for 'tokio'. Use actionbook MCP to get lib.rs selectors, then agent-browser to fetch. Return: name, version, description, features."
   )
3. Wait for agent or continue with other work
4. Summarize results to user

Example: Third-Party Crate Documentation

User: "tokio::spawn documentation"

Claude:
1. Read ../../agents/docs-researcher.md
2. Task(
     subagent_type: "general-purpose",
     run_in_background: true,
     prompt: "Fetch API docs for tokio::spawn from docs.rs. Use agent-browser first. Return: signature, description, examples."
   )
3. Wait for agent
4. Summarize API to user

Example: Std Library Documentation

User: "Send trait documentation"

Claude:
1. Read ../../agents/std-docs-researcher.md  (NOT docs-researcher!)
2. Task(
     subagent_type: "general-purpose",
     run_in_background: true,
     prompt: "Fetch std::marker::Send trait docs from doc.rust-lang.org. Use agent-browser first. Return: description, implementors, examples."
   )
3. Wait for agent
4. Summarize trait to user

Example: Rust Changelog Query

User: "What's new in Rust 1.85?"

Claude:
1. Read ../../agents/rust-changelog.md
2. Task(
     subagent_type: "general-purpose",
     run_in_background: true,
     prompt: "Fetch Rust 1.85 changelog from releases.rs. Use actionbook MCP for selectors, agent-browser to fetch. Return: language features, library changes, stabilized APIs."
   )
3. Wait for agent
4. Summarize features to user

Deprecated Patterns

Deprecated	Use Instead	Reason
WebSearch for crate info	Task + crate-researcher	Structured data
Direct WebFetch	Task + actionbook	Pre-computed selectors
Foreground agent execution	run_in_background: true	Non-blocking
Guessing version numbers	Always use agents	Prevents misinformation

Error Handling

Error	Cause	Solution
actionbook unavailable	MCP not configured	Fall back to WebFetch
agent-browser not found	CLI not installed	Fall back to WebFetch
Agent timeout	Site slow/down	Retry or inform user
Empty results	Selector mismatch	Report and use WebFetch fallback

Proactive Triggering

This skill triggers AUTOMATICALLY when:

• Any Rust crate name mentioned (tokio, serde, axum, sqlx, etc.)
• Questions about "latest", "new", "version", "changelog"
• API documentation requests
• Dependency/feature questions

DO NOT use WebSearch for Rust crate info. Launch background agents instead.