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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine value by disclosing what is returned (plan tier, caps, unlocked sources) and why it matters for downstream quota-consuming calls. It does not discuss rate limits or failure cases (e.g., unauthenticated), which keeps it short of a 5.

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?

Two sentences: the first declares contents, the second declares usage timing and reason. Nothing is redundant and the content of the return is front-loaded before the call-condition.

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?

With no output schema, the description must convey what comes back, and it does so at the level of three content classes. It stops short of describing the shape of those values (e.g., whether caps are numeric limits or structured objects), but an agent can call it correctly with what is given.

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 tool takes zero parameters, so parameter semantics carry a baseline of 4. The description correctly implies no inputs are needed by framing everything around the signed-in researcher.

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 names a specific verb (Show) and resource (the signed-in researcher's plan, per-account caps, unlocked bibliographic sources). It is unmistakably distinct from every sibling, which are all workflow action tools (search, screening, extraction, export).

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?

It states explicitly when to call it: before planning work that consumes quota, and enumerates the affected activity classes (searching, screening, extraction). It supplies the rationale (know the ceilings), so the agent has an ordering rule, not just a purpose.

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