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

Annotations already mark readOnlyHint=true and destructiveHint=false, so the description needn't restate safety. It adds meaningful behavioral context beyond annotations: the call refreshes from the provider and is explicitly not a repeat charge, which is valuable for an agent deciding whether to call it.

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?

Two short sentences with no filler: the first states the action and resource, the second preempts a cost concern. The most important scoping information is front-loaded.

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-parameter, read-only getter with an output schema, the description plus annotations cover input source, safety profile, refresh side effect, and billing. Nothing an agent needs to invoke it 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?

The input schema fully documents generationId, including its source, so the description adds no necessary parameter semantics beyond the word 'by id'. The baseline of 3 applies because schema coverage is 100%.

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 states a specific verb ('Fetch'), a precise resource ('one Image Lab generation by id'), and an additional behavior ('refresh it from the provider'), making it clearly distinct from enumeration siblings like list_image_lab_generations and from getters of other generation types.

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?

It clearly implies this is the singular-getter path when you already have a generationId, and the schema description tells the agent where IDs come from (generate_image_lab or list_image_lab_generations). It doesn't explicitly exclude listing, but the contrast with the list sibling is evident.

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