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

Annotations already convey non-destructive, idempotent, non-readonly behavior, so the description's added context is what counts: it discloses the side effect scope (sidebar, list_chats, API) plus the mutation rules (whitespace collapsed, 80-char cap). It stops short of saying whether a failed rename leaves the old name intact, so not 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?

Four compact sentences with the action and propagation front-loaded, followed by identification, a usage guardrail, and normalization rules. Every sentence carries information; nothing repeats the title or schema verbatim.

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 single-field mutation with no output schema, the description covers effect, identification, guardrail and normalization adequately. It is slightly thin on what happens when neither chat_id nor list_id resolves, and on whether an error is returned for over-long or blank titles.

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%, so the baseline is 3, but the description adds real semantics beyond the schema for the title parameter (whitespace collapsing and an 80-character cap) and explains provenance for chat_id and list_id. The uid/bearer_token auth parameters are left to the schema.

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 ('Rename one of the user's chats') and clearly distinguishes itself from sibling read/list tools like get_chat, list_chats and delete_chat. The propagation note ('shows everywhere the chat appears') further scopes what the operation touches.

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?

'Only rename when the user asks for it' gives an explicit when-to-use constraint, and the description identifies which identifier to use from which producing tool (chat_id from list_chats, list_id from run_ugc_agent). No explicit when-not-to-use case versus delete_chat or reset_conversation, which keeps it from a 5.

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