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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds that the target is the authenticated user (auth context) and, with no output schema present, carries the burden of disclosing the returned fields (email, remaining credits) — useful behavioral detail beyond the annotations.

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?

A single sentence that front-loads the subject (the signed-in user's account) and lists the two returned values. There is no filler or repetition of the tool name.

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-only account lookup with no output schema, the description covers the essential return contents and the implicit auth requirement. It does not mention error or unauthenticated states, but nothing critical for calling the tool 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?

Zero parameters, so the schema contributes nothing to interpret and the baseline is 4. The description correctly implies the tool is argument-free by scoping it to 'the signed-in user' rather than accepting an identifier.

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 names a specific verb (Shows) and resource (the signed-in user's account) and enumerates exactly what is returned: email and remaining verification credits. No sibling tool in the set (calculators, verification actions, buy_credits) overlaps with this account-read capability, so an agent can route to it unambiguously.

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 rather than stated: 'signed-in user's' tells the agent this is a self-account lookup with no arguments, which makes the when-to-use fairly obvious. However, there is no explicit guidance on when to call it versus siblings like buy_credits (e.g. to check balance before purchasing) and no exclusions.

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