search_library

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

No annotations are provided, so the description carries the burden. It discloses the substring matching behavior and gives an example ('dracula' matches 'Bram Stoker's Dracula'), which is crucial for correct use. It also mentions the return fields. It doesn't state read-only nature, but 'search' implies non-mutating.

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 well-structured with purpose, usage, alternative, args, and returns sections. It is slightly verbose but every sentence contributes useful information. No fluff.

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 tool is simple, and the description covers purpose, usage, parameters, and return values. An output schema exists, so the return details are redundant but helpful. It lacks mention of error handling or edge cases, but these are not critical for a search tool.

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?

The input schema has zero descriptions, but the description fully compensates by explaining both parameters: 'query' as title substring and 'media_type' as an optional filter restricted to 'movie' or 'tv'. This adds clear meaning beyond the raw 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 description clearly states the tool searches the user's Plex library for movies and TV shows they already have. It uses a specific verb and resource, and explicitly distinguishes itself from search_media for new content.

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?

Provides explicit usage context ('when a user asks what's in their library or wants to find content they already own') and names the alternative tool (search_media) for new content. This directly guides selection.

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