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

With no annotations, the description carries the full behavioral burden. It discloses a meaningful constraint — verified contacts are 'the only places a reminder can ever be delivered' — and implies a read-only current-state snapshot through the credit/limit feasibility framing. It does not address auth requirements, data freshness, or failure modes, which are notable gaps given annotations are absent, though the 0-parameter read operation is inherently low-risk.

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 sentences, each earning its place: the first specifies the returned fields, and the second states the decision trigger for calling the tool. There is no redundancy with the title or schema, and the most decision-relevant information (delivery constraint) is front-loaded.

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 0-parameter tool with no output schema and no annotations, the description is nearly complete: it states exactly what data comes back and when to call it, which covers everything an agent needs to invoke it correctly. The only shortfall is the absence of detail on data format, freshness, or error behavior, which the missing output schema would otherwise have supplied.

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?

With zero parameters in the schema (100% coverage trivially), there are no parameter semantics to clarify, so the baseline of 4 applies. The description's field enumeration additionally serves as a de facto output contract that partially compensates for the missing output schema.

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 title states a specific verb+resource pair ('Read the account's contacts, credits and limits'), and the description enumerates the exact payload returned: verified contacts, timezone, plan, credit balance, and active-reminder limit. This cleanly distinguishes get_account from the reminder-lifecycle siblings (create_reminder, cancel_reminder, pause_reminder, etc.), which operate on individual reminders rather than account-level 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 second sentence gives explicit when-to-use guidance: 'Read this first if you are unsure whether a phone call is possible or whether there are enough credits.' This states a concrete decision condition for invoking the tool. It does not name explicit exclusions or alternatives, but given the sibling set contains no account-level read competitor, the scoping is clear and adequate.

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