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

Annotations already cover the safety profile (readOnlyHint=true), so the bar is lower. The description adds real context beyond that: authentication comes from a server-configured BT-API-KEY rather than request parameters, and the result reflects the permissions the server actually holds. Return shape is left unspecified, which is a minor gap.

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?

One front-loaded sentence stating purpose and utility, followed by the endpoint reference. No filler or repetition; every clause earns its place.

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 no-parameter, read-only tool this is nearly complete — purpose, auth source, and value are all covered. Without an output schema it could say a bit more about what the returned application payload contains, but nothing critical is missing to call it correctly.

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, which is the baseline-4 case. The description correctly conveys that no input is needed.

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: 'Return the application the configured BT-API-KEY belongs to.' The word 'configured' implicitly distinguishes it from sibling basis_theory_get_application, which takes an explicit identifier, but no sibling is named outright, so this stops short of a 5.

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?

'The fastest way to check which permissions this server actually has' gives a clear, concrete use case. It does not name competing siblings (e.g. basis_theory_list_permissions) or state when not to use it, so it lacks the explicit routing of a 5.

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