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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety burden is carried elsewhere. The description adds genuinely useful behavior beyond that: the app renders the returned result and the chat reply should be kept to one short line, which shapes how the agent's output should look.

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, front-loaded with the action, then the invocation modes, then the reply-handling instruction. Every sentence carries information the agent needs; nothing is padded or repeated from the annotations.

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 read-only UI-launch tool with no output schema and fully documented params, the description covers what an agent needs to call it correctly in each mode. The remaining gap is the unaddressed precedence when both `query` and `fragrance` are provided, plus no guidance on choosing this tool over the search/get siblings.

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 optional parameters are already documented in the schema. The description restates their effect (query runs an in-app search, fragrance takes a slug or UUID for a profile) but adds no format, precedence, or interaction detail beyond that baseline.

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 (Open) and resource (the Noteboxd app UI in ChatGPT), then enumerates the three distinct modes: home screen, in-app search, fragrance profile. No sibling tool opens the UI, so the agent can distinguish this from fragrance_search or fragrance_get without opening a 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 clear intent-to-invocation mapping: no args = home/trending, `query` = search inside the app, `fragrance` = profile view. However, it never says when to prefer this UI-opening tool over the data siblings like fragrance_search or fragrance_get, nor whether the two optional params are mutually exclusive when both are supplied.

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