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

With no annotations, the description carries the full load and does it well: it discloses an authorization model with refusal behavior, the side effects (author, placement and files survive the edit), an audit signal (updated_at visible in get_conversation), and the same input constraints as add_note. It omits what happens on invalid ids, whether prior text is recoverable, and the shape of the response, which keeps it off a 5.

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 comes first, then preservation semantics, then permissions, then input rules – a sensible order with no filler. A few phrases are decorative ('a word that no longer holds') and the note-id sentence trails at the end, but nothing is redundant.

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?

No output schema exists, and the description compensates partly by noting that the correction surfaces as updated_at in get_conversation, alongside authorization and preserved state. What is missing is the actual return value of update_note itself and failure modes, which an agent would still have to discover.

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 100%, so both the id-sourcing convention and the plain-text/10000-character constraint on body already live in the schema. The description restates those same facts ('plain text, up to 10000 characters', 'as notes of get_conversation gives it') without adding format or edge-case detail beyond them, which is the baseline-3 case.

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?

"Replaces the text of an internal note left on a thread" gives a specific verb (replace), resource (note), and scope (text only, not the whole note). It clearly contrasts with siblings like add_note and delete_note because the operation is framed as a text replacement that preserves author, place and files.

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 names concrete triggers (typo, wrong figure, a word that no longer holds) and states who may call it (author, manager, account owner) with refusal for anyone else. It does not explicitly route to add_note for a brand-new note or state when not to use the tool, but the 'replaces' framing plus the add_note cross-reference makes the boundary inferable.

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