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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds valuable context beyond annotations by explaining that contacts are 'the only places a reminder can ever be delivered,' and enumerates the data fields returned. This clarifies the semantic significance of the account data without contradicting 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?

The description is two sentences: the first states what the tool returns, the second states when to use it. Every phrase earns its place and the most decision-relevant information ('verified contacts', 'credit balance') appears first.

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 parameterless read with no output schema, the description enumerates the returned fields and provides a clear use case. The sibling tools are all reminder operations, so there is no missing information needed to select or invoke this tool correctly.

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 has zero parameters, so the schema fully documents the input surface. The description does not need to explain parameters; instead it focuses on the returned data, which is appropriate for a parameterless read.

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 identifies the tool as reading the account's verified contacts, timezone, plan, credit balance, and active-reminder limit. The verb 'read' and the specific data fields distinguish it from the reminder-operation siblings, all of which target individual reminders rather than account state.

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 explicitly states when to call it: 'Read this first if you are unsure whether a phone call is possible or whether there are enough credits.' Since none of the sibling tools provides account-level information, there is no alternative to disambiguate; the guidance is unambiguous and actionable.

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