favorite_photos

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

Annotations already indicate non-read-only, non-destructive, idempotent behavior. The description adds the key context that the tool can both add and remove a favorite state, which is useful. However, it does not disclose error behavior, permission requirements, or effects on non-existent refs.

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 extremely concise, with no filler. The args section is clearly formatted and each line adds value. It earns its place entirely.

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 small 2-parameter tool with an output schema and rich annotations, the description covers the basics. However, it lacks any usage context or error/edge-case information, and does not reference sibling tools, which could leave an agent uncertain about the best tool for a given request.

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%, so the description must compensate. It explains that 'refs' accepts photo UUIDs or exact filenames, and that 'favorite: False' un-favorites. This is essential semantic detail not present in the schema, though filenames could be more specific (e.g., extension format).

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 states the action ('Heart photos') and its inverse ('remove the heart'), with a specific resource ('Photos'). It is easily distinguished from sibling tools like set_photo_title or add_to_album.

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?

No guidance is provided on when to use this tool versus alternatives. There is no mention of use cases, prerequisites, or exclusion conditions. The description only explains what the tool does, not when to choose it.

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