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

Annotations already declare a pure read (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the safety profile is covered. The description adds genuinely useful behavior beyond that: the sidereal rather than tropical convention, that ALL Saturn returns are returned (not just the first), and that birth date and town are mandatory inputs to be requested if absent.

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?

Three short sentences, front-loaded with the usage triggers and closing with the input precondition, so the most decision-relevant information comes first. The quoted keyword list ('Saturn return at 28/29', Shani return) is slightly stuffed but earns its place for query matching.

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?

For a three-parameter tool with no output schema, the description covers what is returned (dates and ages for every Saturn return) and the required inputs. The only soft spot is that it does not mention that birth_time is optional yet improves accuracy, leaving that to 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 description coverage is 100%, so the schema already explains birth_date format, birth_place format, and the optional birth_time with its precision guidance. The description only restates that birth date and town are needed, adding no syntax or precision detail beyond the schema — baseline 3 is appropriate.

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 (returns) and resource (every Saturn return with dates and ages) and pins the reckoning system as Vedic/sidereal, which separates it from the tropical-astrology siblings. It also names colloquial variants (Shani return, 'Saturn return at 28/29') so an agent can match natural user phrasing.

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 explicit trigger conditions: when someone asks when their Saturn return is, whether they are currently in it, or at what ages it occurs. It does not explicitly name the nearest alternative (sade_sati_check, the other Saturn-transit tool), so the agent must infer the boundary, but the stated conditions are clear enough to route correctly.

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