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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the description's added value is what it says beyond them: citations are refused if OCR or metadata changed, and short cvp: ids read only the first 6000 characters of the current page. Truncation limits and validation behavior are exactly the kind of context annotations cannot carry. No auth or rate-limit notes, but that is a minor gap here.

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?

Purpose is front-loaded in the first sentence, followed by the sibling alternative, then validation behavior, then the special id case. Four dense sentences with no filler, though the final sentence crams two distinct behaviors (6000-char truncation and continuation via prossimo_inizio) together, costing some readability.

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?

An output schema exists, so return values need not be spelled out, and the description still flags the notable outputs (fonte_id cv2, prossimo_inizio) and the refusal-on-change behavior. Together with the read_pages alternative and the truncation caveat, an agent has everything needed to call this correctly.

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 the single id parameter, so the description must carry the meaning, and it largely does: id is the same fonte_id seen in search results, while a short cvp: id is a different case that reads the current page and yields a cv2 fonte_id plus prossimo_inizio. The two id dialects are explained, though the exact accepted formats are still inferred.

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 first sentence names a specific action (re-reads the passage identified by id from search results, i.e. the same fonte_id) and the second explicitly distinguishes it from read_pages, which handles full pages. An agent can tell what this tool returns and how it differs from the closest sibling 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.

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

It gives an explicit routing rule: a brano is not the full page, so for a whole page or multiple pages use read_pages. It also tells the agent to use the returned cv2 fonte_id for a verifiable citation and prossimo_inizio to continue. It does not address the other citation-adjacent siblings (verify_quote, read_passages), so it stops short of full when/when-not coverage.

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