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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely new operational context: an auth/access prerequisite and the fact that missing or stale charts return an 'unavailable' result rather than erroring — useful preconditions the annotations don't convey.

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?

Four short sentences, each carrying distinct information: payload contents, access precondition, input constraint, failure mode. Front-loaded with what is returned and zero filler.

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 an output schema present, return-shape detail is not required, and the description covers the remaining gaps an agent needs — auth requirement, no-input contract, and the unavailable-result edge case. Nothing material is missing for a zero-parameter read.

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?

Zero parameters sets the baseline at 4, and the description reinforces it by explicitly stating what is *not* accepted (birth details, profile identifiers), preventing an agent from inventing inputs. No further parameter semantics are needed.

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 — returns the connected person's *current saved* natal chart — and enumerates the payload (placements, birth-time uncertainty), which implicitly separates it from calculate_chart. It never names the sibling explicitly, so the distinction is inferred rather than declared.

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?

Gives clear usage conditions: requires account authorization and chart access, and 'Accepts no birth details or profile identifiers' signals this is a read of stored state, not a computation. It stops short of naming an alternative (e.g. calculate_chart) for the case where no saved chart exists, leaving that routing to the agent.

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