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

With no annotations provided, the description carries the full burden and does so: it discloses that the correction is a diff-style note rather than a replacement, that it notifies the recipient, that it reopens a resolved handoff, and that it resurfaces in the recipient's agent list. It also scopes ownership ('a handoff YOU sent'), which is an implicit authorization constraint.

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?

Front-loaded with the action and the gating condition, then the behavioral consequences, then the parameters — a sensible order with no filler sentences. The final sentence is dense, packing ownership, either/or parameter choice and format into one line, which costs a little 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?

For a no-annotation, no-output-schema mutation tool, the description covers side effects, recipient notification, state change and required inputs well. It leaves minor gaps: whether the correction can later be edited or removed, and whether the recipient notification is avoidable.

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 coverage is 67% (handoffId is undocumented there), and the description adds genuinely new semantics by stating 'Provide either `handoffId` or `key`, plus `body` (markdown)' — the either/or relationship between the two identifiers is not expressed in the schema. It does not explain the format of handoffId itself, so it stops short of full compensation.

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?

States a specific verb and resource ('Add a correction to a handoff YOU sent') plus where the correction appears ('shown below the original body'). It explicitly distinguishes itself from the sibling edit_handoff, so an agent can route correctly without opening either 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?

Gives an explicit precondition ('Only call this when the user asks you to') and names the deciding condition versus the alternative: use this when the recipient may already have seen the handoff because 'edit_handoff would be refused'. That is a precise when-to-use and when-not-to-use signal.

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