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

Annotations already signal a write operation (readOnlyHint=false), and the description's 'Add' is consistent with that but not additive. It adds the 'recurring' characterization but does not disclose duplicate handling, side effects, or return behavior.

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 with no filler; the core action is front-loaded and the cadence examples follow immediately. Nothing could be removed without losing information.

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?

The schema covers all 8 parameters and the annotations cover the write safety profile, so a short description is workable. However, with no output schema and no mention of quarterly frequency or return behavior, the description is only minimally complete for a create operation.

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?

Schema description coverage is 100%, so the description is not required to restate parameter meanings. It adds little beyond the schema and actually lists 'monthly, yearly, or weekly' while omitting the schema-supported 'quarterly', which is a minor inconsistency.

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 uses a specific verb ('Add') and a concrete resource ('recurring subscription'), making the tool's core action clear. It does not explicitly distinguish itself from sibling tools, and the parenthetical omits the schema-supported 'quarterly', so it stops short of a perfect 5.

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 intended use is implied: it should be used when the agent needs to add a recurring subscription. There is no explicit when-not-to-use guidance and no mention of alternatives such as list_subscriptions, so the guidance is helpful but not thorough.

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