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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=false. The description adds valuable behavioral context beyond those annotations: it scopes the call to the current API key and explicitly states that it costs no credits, which is operationally useful for an agent managing API budget.

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 a single compact sentence that front-loads the action and resource, then lists the returned fields and closes with the cost note. Every clause carries useful information with no filler.

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 simple zero-parameter read tool with no output schema, the description is sufficiently complete: it states the subject (current API key), enumerates the returned fields, and discloses the no-credit-cost behavior. Annotations cover the safety profile, so nothing critical 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 and the input schema is empty, so the baseline is 4. The description lists returned fields rather than parameter semantics, which is appropriate for a parameterless read tool.

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 gives a specific verb and resource: 'Return the account profile for the current API key', and enumerates the fields included. This clearly distinguishes an account-profile read from most siblings, though it does not explicitly contrast with get_credits, get_usage, or register_account, which overlap partly on credits/usage.

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 implied: fetch account metadata for the current API key. The description adds a useful cost note ('Costs no credits'), but it does not say when to choose this over get_credits, get_usage, or other sibling tools, nor does it state any prerequisites or exclusions.

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