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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the 'Read-only - does not change account state' sentence largely restates structured data. The description does add genuine context beyond annotations: it operates on the implicit authenticated user (no identifiers needed) and reveals the affordability-gating purpose of the returned credits.

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?

Three tight sentences, front-loaded with what is returned and then the workflow guidance. The read-only sentence is slightly redundant with the annotations, but it is short and does not bloat the definition.

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-argument, read-only tool with full annotation coverage and an output schema, the description covers purpose, returned fields at a high level, and the sequencing constraints. Nothing an agent needs to call it correctly 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 schema carries no semantics to supplement; baseline is 4. The description correctly implies no arguments are required by framing the result as the caller's own profile.

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 authenticated user's profile') and enumerates the returned content (email, firstName, lastName, creditsAmount, subscription status), which cleanly separates it from siblings like get_cover_letter_cost or list_user_files.

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?

Explicitly names the workflow: call before create_cover_letter / regenerate_cover_letter, optionally alongside get_cover_letter_cost, and states the preference over asking the user for their balance. Both the when-to-use and the preferred alternative are spelled out.

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