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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds meaningful context by specifying the caller-scoped nature ('the caller's active subscriptions') and the exact return fields, which goes beyond what annotations provide. No contradictions with 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 the purpose and return fields, the second gives usage guidance. Every word earns its place with no redundancy or irrelevant details.

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 list tool with no required params and no output schema, the description is complete: it states scope, what it returns (specific fields), and when to use it. Safety is covered by annotations, and the schema handles the one optional param. Nothing essential is missing.

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% since the only parameter include_inactive has a clear description in the schema. The tool description adds the word 'active' which aligns with the default behavior but doesn't add significant meaning beyond the schema. Baseline 3 is appropriate.

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 the specific verb 'List' with the resource 'the caller's active subscriptions,' clearly distinguishing it from sibling tools like subscribe and unsubscribe. It also enumerates the exact fields returned, leaving no ambiguity about the tool's purpose.

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 explicit use cases: 'to review what you're monitoring before adding more or to find an id to cancel.' This tells the agent when to use it, but it doesn't mention when not to use it or explicitly name alternative tools, though the use cases implicitly distinguish it from subscribe/unsubscribe.

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