list_backups

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

The description states 'Expires snapshots past SPOTIFY_MCP_BACKUP_RETENTION_DAYS' and 'reports what it removed', which is a mutating action. The annotations declare readOnlyHint=true, which claims the tool does not modify state. This is a direct contradiction. Per the rubric, score is 1 because the description contradicts annotations.

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 dense but efficient, with the core listing behavior front-loaded. It includes necessary operational details (sidecar reads, retention policy, output fields) without being verbose. Could be slightly tighter, but overall well-structured.

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?

The description covers the tool's main actions (list, expire, report removal) and specifies the output envelope fields. It does not describe the response_format effect beyond the schema, but that field is fully documented. The only weakness is the annotation contradiction, which creates ambiguity about safety, but the description itself is fairly complete.

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% for the single parameter (response_format). The description does not need to add parameter details, so the baseline of 3 applies. The schema already explains concise/detailed/json.

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 a specific verb and resource: 'List complete and partial library backups (newest first)'. It also lists secondary behavior (expiring old snapshots) which distinguishes it from similar tools like backup_library or delete_backup. It is unambiguous what this tool does.

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 implies usage for inspecting backups and cleaning expired ones, but it does not explicitly contrast with alternatives like delete_backup (which also deletes) or backup_library (which creates backups). When to choose this over a plain delete tool is left to inference, so guidance is only moderate.

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