get_subscription

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered structurally; the description adds value by stating the 'billing:read' scope requirement and by disclosing that the response includes upgrade paths, Agency extra-account state and next steps. It stops short of noting any rate limits or failure modes, so it earns a 4 rather than a 5.

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?

Well front-loaded: what it returns comes first, then when to call it, then constraints. The middle sentence is dense and slightly overloaded with parentheticals ('plan tier plus any extra slots'), but every clause carries real information rather than restating the 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?

With no output schema, the description does the work of describing the payload contents and even hints at actionable next steps. Only the shape of 'the exact next steps' and the ordering of the plans list remain unspecified, which is a minor gap for an otherwise thorough definition.

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?

There are zero input parameters, so there is no parameter semantics to explain and the baseline of 4 applies. The description instead spends its words on output semantics, which the schema cannot carry.

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?

Names a specific verb and resource (get the caller's subscription) and then enumerates the exact fields returned: status, tier, cancel-at-period-end, period end, trial end, pause state, connected accounts and account limit. It also separates itself from upgrade_subscription / cancel_subscription by being explicitly the read-only status entry point.

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?

Gives explicit when-to-use triggers in the user's own words ('upgrade', 'change plan', 'add accounts', 'how many accounts') and an ordering directive: 'Call this FIRST'. That is precisely the routing information an agent needs when several subscription siblings exist.

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