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

Description adds significant behavioral context: authentication requirement (Pipeworx OAuth), delivery channel specifics (always-on feed, optional email/SMS with phone verification and 10/day cap, webhook with HMAC signing), and example configurations. Annotations indicate idempotentHint=true but description implies each call creates a new subscription (returns new id), which could be ambiguous but not a direct contradiction.

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 a single dense paragraph; it front-loads the main purpose and key requirements. However, it could be more scannable with bullet points or separate sections for types and channels. No wasted sentences, but structure could improve readability.

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?

Given the complexity (multiple subscription types, delivery channels, authentication) and no output schema, the description covers the core functionality: it explains what the tool does, what it returns (subscription id), prerequisites, and examples. It lacks mention of failure modes or idempotency behavior, but is generally complete for an initial understanding.

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 100% schema coverage, the description still adds substantial value: for each type enum, it provides concrete examples and explains parameters (e.g., sec_8k with ticker and items, polymarket_edge with topic). For delivery, it elaborates on webhook signing and SMS cap, which are not in the schema. This goes well beyond the schema descriptions.

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?

Title 'Subscribe to Alerts' and description 'Create a proactive monitoring subscription to a live-data event stream' clearly state the verb (create) and resource (subscription). It distinguishes from sibling tools like list_subscriptions, unsubscribe, and recent_alerts by focusing on creation of a subscription.

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?

Description explicitly mentions requirement for a Pipeworx OAuth account, notes that anonymous and BYO accounts cannot persist subscriptions, and lists supported types and delivery channels. It implicitly guides when to use: when you need proactive monitoring. However, it does not explicitly state when not to use or alternative options beyond the type list.

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