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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered structurally. The description's genuine addition is the billing context (20 credits, Tier 2) and the group tag, which is useful but thin; it says nothing about computation behavior or constraints beyond that.

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?

A single front-loaded sentence lists the computed outputs with no filler, followed by compact group and cost tags. Nothing is wasted, though the tags are metadata rather than explanatory content.

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 needn't be described, and the rich body schema covers inputs. For a read-only calculation tool the description is adequate, with only the sibling-routing guidance 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 description coverage is 100%, so the schema already documents body, fields, and precision thoroughly, including the natal-plus-target-date structure. The description adds no parameter-level detail beyond what the schema provides, 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?

The description gives a specific verb ('Calculate') and resource ('annual profections') and enumerates the concrete outputs: profected Ascendant, lord of the year, activated house, and monthly sub-rulers. This distinguishes it from sibling techniques like progressions, returns, directions, and firdaria by naming the technique, though it never explicitly contrasts with those siblings.

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?

There is no when-to-use guidance: nothing tells the agent when to pick profections over firdaria, progressions, or the various return tools, nor does it explain the role of the required target date in driving the annual calculation. Usage is only inferable from the technique name.

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