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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered; the description reinforces rather than repeats by adding the real gating constraint — a free AstroCalc sign-in and a pre-existing saved profile on the account. That auth prerequisite is genuinely new information an agent needs. It stops short of describing failure behavior when a profile name is unknown, which keeps it from a 5.

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 content is front-loaded: what is returned comes first, then when to use, then the saved-vs-typed distinction. Every sentence carries routing or prerequisite information, though the final sentence is a dense list of five sibling names that borders on heavy. Slightly longer than ideal but no 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?

For a two-parameter read tool with no output schema, the description supplies the return shape indirectly ('Same shape as free_kundli'), the eligibility rule (saved profiles only), the auth requirement, and the alternative for unsigned-in users. Nothing an agent needs to select and call this correctly is 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 coverage is 100%, so the profile (name as listed by my_profiles, or id) and lang enum are already fully documented in the schema. The description adds the useful framing that the profile must resolve to a saved chart and points to my_profiles as the source of valid values, but adds no syntax or format detail beyond that. Baseline 3 is appropriate when the schema carries the parameter burden.

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 names a specific verb and resource ('Summary of one saved person's birth chart') and enumerates the actual content of the result: Lagna, Moon sign, nakshatra, Mahadasha/Antardasha with dates, notable yoga and its rarity, and strong/weak life areas. It explicitly distinguishes itself from free_kundli as the saved-profile counterpart with the same shape, so an agent can tell the two apart without opening either 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?

Usage is spelled out with concrete triggers ('when the user asks about themselves or a saved family member: personality, a child's nature, strengths, what to work on, why life feels a certain way') and an explicit exclusion: only people saved on the account are eligible. It also names the fallback path for non-saved people (birth details typed in chat via free_kundli, kundli_milan, explain_dasha, full_chart, life_timeline).

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