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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered and the trailing "Read-only." is redundant. The description does add genuinely new behavioral context not in the annotations: the session sign-in requirement, which determines whether the call will succeed at all.

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 compact sentences: the returned payload is front-loaded first, the precondition second. Every clause carries information; even the short "Read-only." tag is only marginally wasteful.

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 zero-parameter read tool with full annotation coverage and an output schema, the description covers the one thing structured fields cannot: the sign-in precondition. Listing the fields is slightly redundant against the output schema but not harmful, so nothing an agent needs is 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?

The tool takes zero parameters, so the baseline is 4. The description correctly adds no parameter discussion, and the field list it provides refers to return data rather than inputs, so there is no confusion introduced.

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 signed-in customer's profile") and enumerates the exact data returned (name, phone, email, language, loyalty tier, total orders, member-since). This clearly separates it from siblings like auth_status or get_addresses without needing to open a schema.

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 gives a precondition ("Requires the customer to be signed in for this session") which implies when it can be used, but it never explicitly routes the agent to siblings or states exclusions. In particular it does not mention auth_status as the way to check sign-in state before calling, leaving the choice to inference.

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