Tool · Claude Code · Anthropic

Read

claude-code/readRead · primarysourcechecked 2026-09-02
What matters here3 invariants · all hold

The facts the registry marks decision-changing, with how the other implementations answered. An invariant may be shown as pass/fail; a design choice never is, however unusual it looks.

How this differs from most implementations

Derived by comparing every recorded value against the other implementations of the same capability. Differing is not a defect unless the row is marked an invariant.

Description, as the model sees it

Not recorded yet — the verbatim description has not been captured for this tool.

Registered schema

Not recorded yet — the schema as registered has not been captured for this tool.

Observed · Read

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FactThis toolAcross all implementations
Output shape3 of 3 recorded
Dedicated read toolReadsrc
Line numberingN + TABsrc
Matches the output of cat -n.
like 2 of 7N: ×2 · none ×2 +12 unverified
Output wrapperplainsrclike 6 of 9<path>/<type>/<content> ×2 · raw stdout ×1
Limits3 of 4 recorded
Default line cap2000srclike 6 of 81000 ×1 · none ×11 unverified
Byte / char cap—6 others recorded50 KB ×3 · 100 KB ×1 +22 unverified
Per-line cap2000 charssrclike 4 of 5none ×12 unverified
Whichever hits firstlinessrconly one of 6lines or bytes ×4 · chars ×12 unverified
Pagination3 of 5 recorded
Offset base1-indexedsrclike 7 of 80-indexed ×1
Announces truncationinvariantholdssrc
Emitted on truncation.
all 7 hold1 unverified
Continuation hinton truncationsrconly one of 7(Showing X-Y of N. Use offset=Z) ×2 · (truncated) ×1 +31 unverified
Reports total lines?4 others recordedyes ×2 · linesShown[] ×1 +14 unverified
Out-of-range offset?2 others recordedexplicit error w/ line count ×26 unverified
Non-text6 of 6 recorded
Binary content never enters context silentlyinvariantholdssrc
Refuses binary files.
4 of 5 holdfalse ×14 unverified
Binary filesrefusesrconly one of 5error: Cannot read binary file ×2 · raw bytes into context ×1 +14 unverified
Imagesinlinesrconly one of 9attachment (jpeg/png/gif/webp) ×1 · attachment + mime sniff ×1 +6
PDFspages param, max 20/reqsrconly one of 5attachment ×2 · page ranges + continuation ×1 +13 unverified
Notebookscells + outputssrconly one of 2(notebook-edit tool) ×16 unverified
Giant single lineper-line capsrclike 4 of 7char budget absorbs it ×1 · none ×1 +12 unverified
Errors3 of 4 recorded
Missing patherrorsrconly one of 4Did you mean one of these? ×2 · shell error ×15 unverified
Path is a directoryerrorsrconly one of 4lists entries ×2 · lists ×15 unverified
Empty fileexplicit remindersrconly one of 2empty stdout ×17 unverified
Non-vision model—2 others recordedexplicit note in output ×1 · requires image-capable model ×15 unverified
Correctness2 of 3 recorded
Mixed line endings?2 others recordedraw ×1 · renders CR visibly ×17 unverified
Staleness check before writeinvariantholdssrc
Edit requires a prior read of the same file.
3 of 9 holdfalse ×6
Line-number contamination guardinstructs model to strip prefixsrconly one of 2write-side detector rejects N| content ×1

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names verbatim, as registered