look_at_photos

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

Given the annotations already declare the operation read-only and idempotent, the description adds genuinely useful behavior: it renders thumbnails, returns an image, and works for iCloud-only photos by reading Apple's local thumbnail cache rather than the original. This tells the agent an important implementation detail beyond the structured hints.

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 description is compact: one functional summary, one targeted usage instruction, one implementation note, and two parameter definitions. Every sentence earns its place and the most important 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 simple two-parameter rendering tool, the description covers what the tool does, when to use it, how it behaves for iCloud photos, and both parameter meanings. The only minor gap is that with no output schema it does not specify how multiple refs are packaged in the returned image output, though the workflow is still clear.

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 0%, and the description fully compensates by explaining that refs accepts photo UUIDs from search results or exact filenames, and that size is the longest edge in pixels with a 128-2048 range. This is exactly the meaning an agent needs and is not present in 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?

The opening sentence names the specific action ('renders each one') and the resource (photos), and explicitly states the output is an image. This distinguishes it from search_photos and export_originals, which either locate or export originals rather than render thumbnails.

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?

The description gives an explicit trigger: use on the top few results of every search before answering a 'find my photo of X' question. It does not explicitly mention when not to use it or name alternatives, but the workflow context is clear.

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