Get z-library download URL

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

No annotations are present, so the description carries full responsibility—and it delivers: discloses short-lived session-bound links, no caching/reuse, daily allowance consumption, and the server's inability to save files unless an env var is set. This is exceptional behavioral disclosure for a tool with zero 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?

Four sentences, each earning its place, with the primary action stated first. Slightly long due to the environment variable note, but no redundant filler.

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?

Covers input provenance, link lifetime, usage constraint, allowance impact, and prerequisite server configuration. Missing explicit error behavior or response shape details, but the tool's output is simple (a URL) and no output schema exists.

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 both book_id and hash already described, including the 'must match' relationship. The description reiterates that they come from a zlib_search result but adds no new semantic detail beyond what the schema already provides.

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?

States a specific verb and resource ('Get a direct download URL for one book') and identifies the required inputs (id and hash from zlib_search). This clearly differentiates it from siblings like zlib_search, zlib_limits, and zlib_login.

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?

Clearly indicates when it should be used: after obtaining a zlib_search result, and warns to use the link immediately without caching or reuse. It also notes the allowance consumption and points to zlib_limits, though it doesn't explicitly state when not to use it.

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