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

Annotations already declare the write/open-world/non-idempotent profile, and the description usefully adds the endpoint path and a cost of 10 credits (Tier 1), which the agent needs for budgeting. However it does not disclose delivery semantics, retry behavior, whether repeated calls create duplicate subscriptions (consistent with idempotentHint=false but unstated), or how long 'N' defaults to, leaving real behavioral gaps for a mutation tool.

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?

Very short and front-loaded: the event sentence comes first, then bracketed metadata for group, endpoint, required field, and cost. The bracket block is scannable and earns its place for cost and endpoint; minor redundancy in repeating the required parameter.

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?

An output schema exists, so return values need not be explained, and cost plus endpoint are covered. But for a webhook-registration mutation the description omits the semantics of the lead-time window, duplicate handling, and lifecycle management, which is the information an agent most needs beyond the schema.

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 67% and the description adds essentially nothing: '[Required: url]' merely restates the schema's required list, and it says nothing about URL validation, HTTPS requirements, or reachability checks despite being the sole required argument. The two optional compaction parameters are fully documented in the schema itself, so the baseline 3 applies.

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 event and domain: a webhook that fires N days before the end of a Vimshottari mahadasha. The event type distinguishes it well from the many sibling webhook tools (retrograde_end, dasha_change, sign_ingress), though the description describes the firing event rather than the act of registering, which the title supplies. An agent can identify the tool's function without opening the schema.

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?

No guidance on when to register this webhook versus siblings like astroway_webhooks_dasha_change, and no mention of prerequisites, whether duplicate registrations are allowed, or how a listener is later removed (no delete tool is named). Critically, the 'N days' window is never explained and no parameter exposes it, so the agent cannot tell how the lead time is configured.

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