List items in progress

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

Annotations already declare readOnlyHint=true, so the bar is lower. The description adds: ordering (newest first), the fact that progressLastUpdate is included but position is not, and podcast episode naming. This goes beyond the annotation but still lacks details about pagination limits (beyond the parameter), response shape, or error conditions. With no output schema, more could be said, but the added context is adequate.

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?

Three sentences, each earning its place: main purpose, limitation vs. alternative, and podcast-specific detail. No fluff, front-loaded with the core functionality. Excellent conciseness.

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 read-only list tool with no output schema, the description covers: what is returned (entries with progressLastUpdate, recentEpisode for podcasts), what is not returned (position), ordering, scope (all libraries), and an alternative tool. Minor gaps: no mention of user context (clearly the current user) or that limit is the only pagination mechanism, but these are reasonable inferences. Nearly 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 coverage is 100% with both parameters fully described (limit with default/range, detail with enum and explanation). The tool description does not add any extra meaning beyond the schema, so it meets the baseline of 3. No need for more given the schema already does the job.

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?

Description states specific verb ('list') and resource ('items in progress' across all libraries), explicitly calling it the 'Continue Listening' list. It distinguishes from siblings by mentioning get_media_progress for position data, and its unique scope (progress across libraries) sets it apart from other list tools like list_libraries or list_library_items.

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?

Explicitly tells the agent when to use an alternative (get_media_progress for positions) and clarifies that entries carry progressLastUpdate but not position. It also describes podcast-specific behavior (recentEpisode field). However, it does not compare to other sibling list tools (e.g., when to use this vs. list_recent_episodes) nor explicitly state prerequisites, but the context is clear enough.

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