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 "with its configuration" as a hint about return content, but says nothing about auth requirements, missing-id/404 behavior, or the REST endpoint's failure modes. Modest added value against a lowered bar.

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 short sentences, front-loaded with the operation and then the REST mapping. Nothing is padded, though the "Basis Theory: GET /reactors/{id}" clause is largely redundant for an agent that already has the name and schema.

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?

A simple one-parameter read tool with readOnlyHint annotation and no output schema; the description covers what it returns at a high level and needs no return-value detail. Complete enough for correct invocation, with only failure/auth context missing.

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%, so the single reactor_id parameter is already documented as "The reactor's id." The description adds no format, syntax, or sourcing guidance beyond the schema, so the baseline 3 applies.

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 (Fetch) and resource (a single reactor) plus the payload content (its configuration), which cleanly separates it from list_reactors. However, it does not name or contrast with any sibling tool by name, so differentiation is implicit rather than explicit.

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?

"single reactor" implies the when-to-use case relative to the sibling basis_theory_list_reactors, but the description never states that contrast, prerequisites, or exclusions. Usage is inferable from the wording alone, which is the minimum viable level.

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