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

Annotations already declare destructiveHint=true, but the description goes well beyond them: it discloses that the whole thread plus all its messages are destroyed (cascade), that document_range anchors also lose their document mark, and that this cleanup is best-effort with failures surfaced via `markStripNote` rather than blocking deletion. That is precisely the destruction scope and failure-mode context annotations cannot express.

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 sentences, each earning its place: the core action and scope first, the sibling contrast second, the document_range edge case and its non-fatal failure semantics third. Front-loaded and free of filler.

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?

There is no output schema, but the description covers what gets destroyed, the alternative operation, the anchor-specific side effect, and the failure-signaling field (`markStripNote`). Nothing an agent needs in order to invoke this destructive tool correctly is missing.

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 threadId's cascade behavior and expectedProjectId's targeting/access-refusal semantics are already documented in the schema. The description adds no parameter syntax, format, or interaction detail beyond that, so the baseline of 3 applies.

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 ('Deletes a thread and all its messages') plus the cascade scope, and explicitly contrasts itself with the sibling resolve_comment. An agent can distinguish it from resolve_comment, move_comment, and reply_comment 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?

Names the alternative operation (resolve_comment) and states the discriminating condition: it resolves without deleting, this one deletes. That is exactly the when-to-use-this-vs-that guidance an agent needs, with no inference required.

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