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web_fetch

Read-only

Read a selected HTML document as bounded Markdown, preview or expand a specific excerpt, and manage returned text length for model context.

Instructions

Read one selected HTML document as bounded Markdown text.

USE THIS when you already know which document you want to read, preview, or
expand around a collected excerpt. If you know the source but need to find
its chapter, appendix, next page, reference, or related document first, use web_links instead.
If you do not yet know a source, use web_search.

Preview with max_chars=500 to limit model context; this does not reduce the
initial network download. When more retained text is useful, copy
continuation.arguments into the indicated tool rather than recalculating the
next offset. Null continuation means the retained text has ended.

continuation and excerpt.expand use expected_content_hash. If the retained
text version changed, content_changed returns no slice: reacquire the document
and choose coordinates again. A matching hash protects coordinates, not
origin freshness.

A page can have too little readable text for web_fetch while still exposing
useful ordinary HTML links through web_links; treat such pages as possible
navigation hubs instead of assuming the source has no usable structure.

Returns content, title, final URL, source category, Unicode-coordinate paging,
cache/hash fields and continuation. truncated means more retained text can be
continued; text_truncated means a tail was discarded by the hard retention
ceiling and cannot be recovered by pagination. Expected failures return
{error, hint}.

Input Schema

TableJSON Schema

Name	Required	Description
`url`	Yes	HTTP(S) page URL, a search result.url or research source.url. Supports HTML/XHTML; no PDF or JavaScript rendering.
`max_chars`	No	Maximum returned characters: default 10000, configured cap 20000. Use 500 for preview. Ready actions include a budget; smaller output saves context, not the initial download.
`start_offset`	No	Unicode-character offset; default 0. Ready continuation/expand arguments provide it. For manual reading, use next_start or excerpt.start_char.
`expected_content_hash`	No	Optional retained-text version guard. Ready actions supply it; mismatch returns content_changed without a slice. Omit for unguarded reading.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.4Oct 4, 2026

TDQS

A4.8/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only cover readOnlyHint and openWorldHint, and the description goes well beyond them: preview does not reduce the initial download, continuation/excerpt.expand require expected_content_hash, a mismatch returns content_changed with no slice, and the hash protects coordinates rather than origin freshness. It also distinguishes truncated from text_truncated (recoverable vs unrecoverable tail) and notes expected failures return {error, hint}.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core purpose, then layered usage, preview guidance, hash semantics, and return-shape notes; each paragraph carries distinct operational information. It is dense and slightly long, but almost no sentence is redundant with the schema or annotations.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 4-parameter read tool with an output schema and annotations, the description covers routing, paging, truncation semantics, hash guarding, and failure shape. Even the edge case of a page with too little readable text (treat as a navigation hub, try web_links) is addressed, leaving no operational gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the schema already documents each parameter; the description nevertheless adds cross-parameter semantics the schema lacks, notably that the hash guard protects coordinates rather than content freshness and that continuation.arguments should be copied rather than the next offset recalculated. It stops short of adding new per-parameter syntax, so it stays just above the baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Read one selected HTML document as bounded Markdown text') and explicitly differentiates itself from both siblings: web_links for finding a chapter/page within a known source, web_search for when no source is known. An agent can route correctly without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives explicit when-to-use ('you already know which document you want to read, preview, or expand around a collected excerpt') plus two named alternatives with the exact conditions that select them. Also prescribes the preview workflow (max_chars=500) and the continuation protocol.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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