# Agent-Facing Tools

pi-lens registers the following tools with the pi agent. Most are also exposed
through the MCP mirror (`clients/lens-engine.ts` is the seam both adapters
share) — current exceptions: `ast_grep_outline` and `ast_grep_dump`
(module_report supersedes them for discovery). `read_enclosing` gained MCP
parity (`pilens_read_enclosing`) as of #536, closing #522 item 1.

**Dynamic tooling.** Six tools stay always-active: `lens_diagnostics`,
`lsp_diagnostics`, `module_report`, `read_symbol`, `read_enclosing`,
`symbol_search`. Five situational tools — `ast_grep_search`, `ast_grep_replace`,
`ast_grep_outline`, `ast_grep_dump`, `lsp_navigation` — are registered but
inactive by default; the model activates the ones it needs via the always-active
loader tool `pi_lens_activate_tools`, per pi's dynamic-tool-loading API
(`pi.setActiveTools`/`pi.getActiveTools`). Feature-detected: on hosts without
that API, the five situational tools fall back to being statically active,
exactly as before (`tools/activate-tools.ts`, wired in `index.ts`).

## Per-edit

- **`lens_diagnostics`** — Cached diagnostic state for the current session.
  Modes: `delta` (current turn), `all` (resurfaces stale blockers dropped from
  turn context), `full` (project-wide scan).
- **`lsp_diagnostics`** — File- or directory-scoped LSP diagnostics via the
  active language server.
- **`lsp_navigation`** — IDE-style navigation: `definition`, `references`,
  `implementation`, `typeDefinition`, `declaration`, `rename`, `rename_file`,
  `hover`, `documentSymbol`, `workspaceSymbol`, `signatureHelp`,
  `prepareCallHierarchy`, `incomingCalls`, `outgoingCalls`, `executeCommand`,
  and `capabilities`. Position-based operations accept a `path`/`line`/`character`
  triple. `documentSymbol` accepts a `kinds` filter (e.g. `function`, `class`)
  and a `maxResults` cap (default 20, max 100) to keep large files bounded.
- **`ast_grep_search`** — AST-aware structural search across ~40 languages via
  the `sg` CLI. Supports metavariables (`$VAR`, `$$$ARGS`), `strictness`
  modes (`smart`, `relaxed`, `ast`, `cst`, `signature`, `template`), structural
  constraints (`insideKind`, `hasKind`, `follows`, `precedes`), raw YAML `rule`
  passthrough, `validateOnly` for compile/shape checks without scanning project
  files, and pagination via `skip` / `maxMatches` (per-call cap, default 50,
  max 200; also sets the pagination step). `groupByFile: true` renders a compact
  one-line-per-file distribution (`L<line>:<col>` locations) instead of each
  match body — for high-volume searches. `pattern` is optional when a `rule` is
  given.
  Results include `details.matchLocations[]` — each hit carries a ready
  `readSlice` (`path`/`offset`/`limit`) for a bounded context read; zero-match
  results include a `suggestedDump` hint pointing at `ast_grep_dump`.
- **`ast_grep_replace`** — AST-aware structural replace. Re-validates the pattern
  against the current file before writing and reports a clear error if the
  file changed since the preview.
- **`ast_grep_dump`** — Dumps the raw tree-sitter AST for a source snippet. Use
  this when an `ast_grep_search` or `ast_grep_replace` pattern returns zero
  matches and the correct node kind or field name is unknown. `includeAnonymous`
  shows punctuation/CST nodes.
- **`ast_grep_outline`** — Syntax-only code structure (symbols, imports, exports,
  members) for files or directories via `ast-grep outline`. Fast, local, no
  index/LSP/cross-file semantics. Supports `items`/`view`/`type`/`match`/
  `pubMembers`/`globs`; returns per-file `items[]` (nested `members[]`) with
  ready `read` args. Prefer `module_report` for pi-lens-aware navigation; reach
  for this when the syntax tree's own view is enough or pi-lens's extractor is
  weak for a language.

## Project intelligence

- **`symbol_search`** — Ranked identifier search over the persisted word index
  (BM25 + priors demoting tests/vendor/docs, optional graph-centrality boost).
  Answers "which files are most relevant to `<query>`" by identifier — the
  first step of the discovery funnel: `symbol_search` finds candidates,
  `module_report` explains one, `read_symbol` reads its body. Complements
  `grep` (raw substrings) and `lsp_navigation` (exact references). Returns
  `available: false` with a retry hint when the index isn't built yet — it
  self-builds in the background and never blocks the call. See
  [docs/word-index.md](word-index.md) for how the index is built and kept
  warm.
- **`module_report`** — Navigable outline of a file: every symbol's name/kind/
  startLine/endLine/signature, exported vs internal split, class/interface
  member nesting, who-uses-this, fanout/complexity risk flags, and a
  `recommendedReads` top-3 ranked by usage + complexity. No per-symbol `read`
  block (#512) — `offset`/`limit` are pure derivations of `startLine`/`endLine`
  on the report's own `path`; to read a symbol call `read`/`read_symbol` with
  `offset=startLine, limit=endLine-startLine+1` on that path. Cross-file
  entries (`blastRadius.files[].read`, `usedBy[].file`) keep their own path.
  Each entry also carries a first-line `doc` summary (whitespace-collapsed,
  ~120 chars) extracted from an attached doc comment when the language uses
  tree-sitter's conventional `comment` node — JS/TS is the primary target;
  languages sharing that node shape (confirmed: Python, and any grammar whose
  comment nodes are plain preceding siblings) get it for free with no
  per-grammar query work. `exported` stays a boolean field only — it is NOT
  also repeated inside `flags` (#512); `flags` carries only non-derivable
  signals (`async`, `high fanout`, `high complexity`, `boundary wrapper`).
  Each entry carries a `decorators[]` array — the declaration's
  decorators/attributes/annotations (`@app.get("/x")`, `#[tokio::main]`,
  `@Override`) — so the agent reads a symbol's role (route/test/fixture/
  entrypoint) without opening the body. Also emits a `callbacks[]` section for
  high-signal inline executables (event handlers, timers, promise callbacks,
  object/dict function props, assigned closures) with stable synthetic
  handles and flags. The optional `focus` string re-ranks `recommendedReads`
  without expanding scope. `callbackSupport` (`tuned`/`generic`) reports
  whether language-specific callback rules applied — the callback *node
  kinds* are language-uniform, but the semantics are per-language (JS/TS-tuned
  by default, plus Go goroutine/defer, Python scheduler/future lambda, Rust
  spawn/move-closure, Swift weak/strong-self capture, C++ by-reference-
  capture, Kotlin coroutine-builder, Java thread/executor/listener, and C#
  Task.Run/event-`+=` slices); named symbols span all tree-sitter
  `SYMBOL_QUERIES` languages. Pass `view: "summary"` for a smaller orientation
  payload (top-level entries + recommendations, heavy callback/usedBy/
  blast-radius payloads omitted); pass `view: "compact"` for a line-oriented
  TEXT rendering of the full report (cheapest option — roughly a quarter of
  the JSON cost, same underlying data). Reports section-level `provenance`
  for syntax, cached-graph, and heuristic sections. Pass `blastRadius: true`
  for cross-file transitive dependents (read-only over the cached graph).
- **`read_symbol`** — One symbol's verbatim source body, by name or by a
  `module_report` callback handle. Returned body is recorded as genuine
  read-guard coverage for that symbol/callback's line range.
- **`read_enclosing`** — Maps a `path` + `line` (from `ast_grep_search`,
  diagnostics, or LSP locations) to the verbatim body of the smallest enclosing
  symbol or callback. Tree-sitter only — no LSP or graph build. Optional `kinds`
  filter and `maxLines` cap; records read-guard coverage for the returned range.
  When the body exceeds `maxLines`, `onOversize` controls the fallback: `error`
  (default) returns metadata only, `slice` returns a bounded partial read around
  the line (size via `aroundLine`, default `maxLines` then 80), and `outline`
  returns the nested symbols/callbacks with read handles.

## Session

- **`lens_health`** — Runtime health, latency telemetry, and current LSP
  status.
- **`lens_project_scan`** — Cheap project-wide scans (knip, jscpd, duplicates).
- **`lens_diagnostics mode=full`** — full project-wide review: LSP + the cached
  heavyweight analyzers (jscpd, madge, gitleaks, govulncheck, trivy, dead-code)
  folded in via `refreshRunners`.