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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds useful content detail (what the report contains) and the underlying endpoint, but says nothing about rate limits, the period covered by the "monthly" figure, or whether reporting is scoped strictly to the calling tenant.

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, zero filler, with the report's contents front-loaded ahead of the endpoint reference. Nothing is repeated from the title beyond what adds specificity.

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 parameterless read tool with an output-less schema, the description covers purpose and content well enough to invoke correctly. It could be more complete by clarifying the reporting window (no way to specify a date range) and whether the data is scoped to the current tenant only.

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 no parameters, so the baseline is 4. The description reinforces that the report is implicitly scoped to the current tenant (GET /tenants/self/reports/usage), which is the only semantically relevant fact left to convey.

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 ("Fetch the tenant's usage report") and enumerates the report's contents — token counts by type and container plus monthly API call volume. This clearly separates it from siblings like basis_theory_get_tenant and basis_theory_list_tenant_members, which return configuration rather than usage metrics.

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?

Usage is only implied by the tool's name and subject matter; there is no explicit when-to-use statement, no exclusions, and no routing to a sibling (e.g., get_tenant for tenant metadata). The unique resource name makes the intent inferable, but the description does not carry that guidance itself.

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