Subscribe Page to Webhooks

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

Annotations already indicate it is not read-only, not destructive, and idempotent. The description adds the behavior of checking current subscriptions when subscribed_fields is omitted, which is valuable. However, it does not clarify whether calling with new fields replaces existing subscriptions or appends to them, which is a potential behavioral ambiguity. It leaves some operational details to inference.

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 concise and front-loaded: the main purpose is stated in the first sentence, followed by a brief parameter list and a usage hint. It avoids unnecessary words and is easy to scan. Every sentence adds valuable 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 description is complete enough for a simple tool with 3 parameters (1 required). It covers the core action, parameter semantics, and a special usage pattern. The lack of an output schema means the description needs to convey enough for an agent to invoke it correctly, which it does. Minor omissions like the replacement behavior are not critical for basic invocation.

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?

The description adds meaningful detail to page_id (specifying it is the Facebook Page ID) and subscribed_fields (providing examples like feed, messages). The schema only gives a generic description for subscribed_fields, and page_id lacks a description, so the tool description compensates. However, it does not mention response_format at all, but the schema already explains its purpose clearly.

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 specific action (subscribes your app to receive webhook updates) and the resource (Facebook Page). It differentiates from sibling tools by focusing on webhook subscription, a unique capability among the many meta_* tools. It also mentions an additional behavior (checking current subscriptions) that adds clarity.

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 clear context for when to use this tool (for subscribing to webhook updates) and includes a specific usage note (calling without subscribed_fields to check current subscriptions). However, it does not explicitly mention alternatives or when not to use this tool. Given the tool's unique purpose, the guidance is adequate but not fully exhaustive.

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