Read & shape context

Choose the right level of detail.

Use a map to navigate, a signature to understand an interface and source text to verify the implementation.

AvailableReviewed September 2026

Choose a representation for the task. Recover the full source when details matter.

Start with intent

ctx_read defaults to auto when you omit mode. Choose a mode explicitly when the task needs a particular representation. For discovery, start with ctx_compose or search so that a read has a clear target.

Mode	Useful for	What to check
`auto`	A general first read	The returned representation may omit detail
`map`	File structure and API navigation	Bodies are not the full implementation
`signatures`	Function and type interfaces	Language/parser support affects extraction
`full`	Full-file inspection	Cache and output processing can still affect delivery
`lines:N-M`	A known region	Use the correct line range for the current file
`diff`	Changes since the cached read	Compares the read cache, not Git HEAD; use `git diff` for repository changes
`task`	Task-focused selection	Relevant-looking lines may omit dependencies
`entropy`	Dense information in a large file	Ranking is a heuristic
`aggressive`	A compact first representation	Recover details before making exact edits
`reference`	Reference-oriented delivery	Follow the returned recovery instructions

The advertised mode list is not a closed enum. The reviewed parser also accepts these more specific representations:

Mode	Behavior
`raw`	Exact text without the usual framing
`full-compact`	Headerless text with trailing whitespace removed
`anchored` / `anchored:N-M`	Full text or a range with line/hash references for editing
`lines:5,10-20`	Several selected lines or ranges in one read
`lines:-20`	The last 20 lines of the file
`cognitive`	A semantic chunk representation
`mdl`	A structural description
`density:0.40`	A target-density compressed representation

Density and semantic modes are lossy views, not accuracy guarantees. The parser validates mode syntax; range selections use one-based, inclusive line numbers. See the exact read schema for the other inputs.

Read, then zoom in

These are MCP calls:

{"name":"ctx_read","arguments":{"path":"src/main.rs","mode":"signatures"}}

{"name":"ctx_read","arguments":{"path":"src/main.rs","mode":"lines:20-60","fresh":true}}

Use a range returned by your own search or signature view. The numbers above illustrate the argument format.

Exact text and edit anchors

raw: true requests verbatim content and a fresh read. It does not disable access boundaries or downstream security policies.

mode: "anchored" provides line/hash references for ctx_patch. Re-read after a conflicting edit; stale anchors are not a reason to force an overwrite.

Understand caching

An unchanged repeated read may return a compact reference. fresh: true bypasses the read cache, but is not the same as requesting raw text. If the answer needs an omitted detail, recover it rather than assuming the compact representation contains everything.

For shell archives and cached originals, continue with caching and recovery.

Sources & versions3 references Reviewed 18 Sept 2026

mode.rsrust/src/tools/ctx_read/mode.rsReviewed checkout
file_io.rsrust/src/tools/ctx_read/file_io.rsReviewed checkout
ctx_read.rsrust/src/tools/registered/ctx_read.rsReviewed checkout

Core checkout: 5198ea1867
Installed runtime: 3.10.2
SDK release: 1.1.0

Separate baselines for source, CLI/configuration and SDK contracts. Review does not certify every platform or integration.

Versions & compatibility