Exchange z-library credentials

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

With no annotations, the description carries the full behavioral burden and does so well: it discloses that the password is never stored, logged, or returned, that the returned credentials are long-lived, and that the server must be restarted. This goes well beyond the schema.

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?

Every sentence earns its place: operation, lifecycle context, security disclosure, and anti-misuse warning. It is front-loaded with the core purpose and avoids redundancy.

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?

Despite having no output schema and no annotations, the description explains what the call returns, how to use the returned values, and the one-time nature of the operation. For a two-parameter setup tool, this is complete and actionable.

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 already documents both parameters fully, so the baseline is 3. The description clarifies the overall purpose of email/password and the long-lived credentials, but adds no additional format or constraint semantics for the parameters themselves.

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 action and resource: 'Exchange a z-library email + password for the long-lived remix credentials (remix_id / remix_key).' It clearly distinguishes itself from the sibling search/download/limit tools by positioning as a one-time setup helper rather than a per-call operation.

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 says when to use ('one-time setup helper'), when not to ('not a per-call login', 'Do not call this before every search'), and what to do after calling (configure ZLIB_REMIX_ID/ZLIB_REMIX_KEY and restart). This gives an agent a clear decision boundary.

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