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

Annotations only indicate readOnlyHint=false and destructiveHint=false, so the description carries the burden of behavioral disclosure. It explicitly states the operatio is create/update and clarifies non-obvious effects: it does not create a verified user account and does not transfer ownership. This adds valuable context beyond the annotations without contradicting them.

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?

The description is concise: two sentences, the first front-loading the 'Agency mode only' condition and the main verb+resource, the second adding important limitations. No wasted words, and all information is essential.

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 focuses on operation semantics and side-effect limitations, which is sufficient for a simple create/update tool. It does not explain return values or error conditions, but for a tool with a single required parameter and clear schema descriptions, completeness is adequate. The limitation about not creating a verified account adds needed context.

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 all three parameters have descriptions. The tool description does not add any extra parameter semantics beyond the schema; it only mentions the client record context. The baseline of 3 applies because the schema already documents the parameters.

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 clearly states a specific action ('create or update a client record') with a defined resource context ('for an account-level agent'). It explicitly distinguishes itself from related operations by noting it does not create a verified Fine Structure user account or transfer ownership, which differentiates it from potential siblings like agency_create_client_app.

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 description provides clear context on when to use it ('Agency mode only') and the target audience ('account-level agent'). It implies differentiation from alternatives by stating what it does not do, but it does not explicitly name alternative tools or provide exclusion criteria beyond the 'Agency mode' restriction.

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