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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false. The description adds genuinely new behavior beyond them: omitting folderId removes the thread from its current folder, which an agent could not infer from the hints alone. It does not cover failure modes (unknown thread/folder id).

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?

A single sentence with no filler, front-loading the primary action and appending the removal mode as a dependent clause. Nothing could be cut without losing a mode of operation.

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 two-parameter tool with full schema coverage, rich annotations, and no output schema, the description covers everything an agent needs to select and invoke it correctly, including the non-obvious omit-to-remove behavior.

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 100% and the schema already documents folderId's omission semantics and threadId's provenance, so the description is largely restating structured data. Baseline 3 applies when the schema carries parameter meaning.

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?

Names a specific verb and resource ('move a thread') and immediately clarifies the dual mode: into a folder, or out of any folder by omitting folderId. No sibling tool shares this purpose, and the folder-removal case is a non-obvious second capability that the description surfaces up front.

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 clear selection criteria for both modes and points to list_folders as the id source. There is no competing sibling to exclude, so the absence of explicit exclusions is not a real gap, though it stops short of stating prerequisites or error conditions.

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