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

Disclosures beyond annotations: ownership enforcement, row deactivation (not deletion), and historical data preservation. No contradiction with annotations (readOnlyHint=false, destructiveHint=false, idempotentHint=true).

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 focused sentences: first states the core action, second adds important constraints and side effects. No redundant 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?

For a simple tool with one parameter and no output schema, the description covers the operation, ownership, effect on data, and connection to another tool ('subscribe'). Complete and sufficient.

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 coverage is 100% with a clear parameter description. The description adds that the id comes from 'subscribe', providing useful context beyond the schema's 'Subscription id (uuid)'.

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 states the action ('Cancel a subscription by id') and distinguishes it from siblings like 'subscribe' and 'list_subscriptions' by specifying the primary operation and effect.

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 provides usage context ('Ownership is enforced — you can only cancel your own subscriptions') and explains the effect ('deactivated, not deleted'), but does not explicitly mention when to use vs. alternatives such as 'list_subscriptions' for finding IDs.

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