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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely non-obvious behavior beyond that: 'Free, no browser session' tells the agent this call costs nothing and opens no Cloud Browser session, which matters for sequencing and budgeting. It does not describe the response shape, but no output schema exists and the enumerated content is listed instead.

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?

The core guidance is front-loaded in the first two sentences, but the opening sentence is a long comma-chained list of what the guide contains, and the trailing enumeration of eight Unsplash actions is bulky relative to its value. Nothing is outright wrong, but the block would be tighter with the content list compressed and the action list moved behind a summary.

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 zero-required-parameter, read-only guide tool with no output schema, the description covers purpose, timing, cost, and scope of applicability well enough to call it correctly. The only gap is that it does not say what happens if the app is unknown or how the returned method should be consumed by the subsequent browser steps.

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 parameters (app, task) are already documented in the schema, including the Unsplash default. The description adds only indirect meaning via the trailing list of Unsplash actions, which hints at what 'app' scopes to, but gives no guidance on how the 'task' parameter changes the returned guide. Baseline 3 is appropriate.

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?

The description clearly establishes this as a pre-flight guide tool: it returns which browser to use, the sign-in link, the step-by-step method, the app's screens/menus/actions, notes, and any dedicated app tools. It distinguishes itself from the browser_* siblings by positioning itself as the thing you call first, though the opening phrasing ('How to work in an app') is a bit noun-like rather than a crisp verb+resource statement.

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?

'Call it before the first browser step in an app' gives an explicit trigger point relative to the browser tool siblings. It also covers the edge case of apps outside Cotlet's catalog getting the general method. It stops short of stating when NOT to call it (e.g. mid-session or when a dedicated unsplash_* tool already covers the action), so it is not a full 5.

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