Rename an album or set its cover

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

Annotations already convey readOnlyHint=false, idempotentHint=true, and destructiveHint=false. The description adds a non-obvious behavioral detail: the cover must already be a media item in the album, otherwise an error is returned. This is genuinely useful runtime behavior beyond what the annotations state.

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 two sentences with no redundant content. It leads with the main purpose and follows with the critical constraint. Every sentence contributes useful information.

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 relatively simple update tool, the description covers the core operation and the main error condition. The schema covers account defaulting and per-field omission behavior. A minor gap is the behavior when both title and cover_media_item_id are omitted, which is not addressed, but this does not meaningfully block correct use.

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%, with clear parameter descriptions for title, accountant, album_id, and cover_media_item_id. The description adds only a small cross-parameter constraint: that the cover must already be in the album, and that the operation can target title, cover, or both. This is modest added value over the schema, so 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 states a specific verb and resource: 'Change an album's title, its cover photo, or both.' This clearly distinguishes it from sibling tools like create_album, list_albums, and add_to_album. The title reinforcement also helps disambiguate it from update_media_description.

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 provides clear context for when to use the tool: renaming an album or changing its cover. It does not explicitly name alternatives or give when-not-to-use conditions, but the operation is distinct enough that a capable agent can infer the appropriate scenario. The note about cover items already being in the album is a useful precondition.

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