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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, so the description is freed to add genuinely new context: per-call authorization checks on the document and revision, host-visible requests, and bytes being excluded from model context. Those are meaningful operational and privacy traits not derivable from annotations. It stops short of explaining return shape or failure modes on authorization denial.

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

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

Three terse sentences, each carrying distinct information (scope, authorization, output handling), with the scope constraint front-loaded. The telegraphic style is efficient and free of waste, though the dropped articles make it slightly harder to parse than it needs to be.

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

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

For a three-parameter tool with zero schema description coverage and no output schema, the description leaves too much unsaid: it never explains how to supply id/revisionId/index, how to detect the end of the file versus the 320-chunk bound, or what is actually returned when bytes are excluded from context. The authorization and host-visibility notes are useful but not sufficient.

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

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

Schema description coverage is 0% for all three required params (id, revisionId, index), so the description must compensate and largely does not. The word 'chunk' plus the schema's index max of 319 faintly implies index is a chunk offset, but id and revisionId are never explained and no usage relation between them (revision-scoped read) is stated.

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

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

The phrase 'App-only bounded owner file chunk' conveys the resource (owner's original file, read in bounded chunks) and the restricted context (app-only), but it is a noun phrase rather than a verb+resource statement, and it never contrasts itself with the sibling read_document_for_app. An agent can guess it fetches raw file bytes rather than document content, but not confidently.

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

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

No when-to-use guidance or alternatives are given. 'App-only' hints at a context restriction but the description never says when this is preferable to read_document_for_app, nor what happens if called outside the app context.

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