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

Annotations only flag it as a non-readonly, open-world, non-idempotent write. The description adds genuinely important behavior: the signing secret is returned once and must be stored, verification uses HMAC-SHA256 over the body in the X-AB-Signature header, and a hard cap of 5 active webhooks applies. 'arena.rank_changed' delivering at most once a day is a further delivery-rate disclosure not covered anywhere else.

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 action is front-loaded and the description is a single dense paragraph with no filler sentences. The parenthetical event glosses make it long and slightly hard to scan, but each clause carries usable 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?

With no output schema, the description correctly covers the key return value (one-time signing secret) and the auth/verification path. It leaves gaps on webhook lifecycle (how to update or delete a registration) and on the five undescribed event types, but for a two-parameter registration tool it is substantially complete.

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%, so the baseline is 3, but the description goes beyond the bare enum by explaining what each event means (e.g., arena.eligible = 'reached the season minimum and are ranked') and by defining 'arena' as subscribing to all five arena events. It does omit explanation for five enum values (verified_position_*, achievement_earned, rank_milestone), which keeps it from a 5.

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?

States a specific verb and resource ('Have Alpha Bazaar POST events to your HTTPS endpoint') and immediately enumerates the subscribable events, so an agent knows exactly what the tool does. No sibling tool touches webhook registration, so the action is unambiguous within the toolset.

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 event catalog and the 'up to 5 active webhooks' constraint imply when to reach for this tool, but there is no explicit when-to-use or when-not statement (e.g., versus polling signals/leaderboards, or what to do once the limit is hit). Usage is inferable rather than stated.

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