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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds real context beyond them: city text is geocoded in memory and never saved, and a guardrail against deterministic relationship claims. It doesn't state what the response contains or how the score is computed.

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?

Roughly two sentences with no filler, front-loaded on the trigger conditions followed by the exclusions. Every clause carries routing or behavior information; slightly dense but appropriately sized.

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 read-only comparison tool with no output schema, the description covers triggers, exclusions, and input conventions well. The mode parameter's meaning and the shape of the returned compatibility output are the only notable gaps.

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 schema already documents date/time/placeName, so the schema does most of the work. The description reinforces placeName semantics ('city text only', no coordinates) but says nothing about the mode enum values (romantic vs friendship), leaving that parameter only describable from the schema.

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 the concrete deliverable (guna milan / ashtakoota score out of 36) and the domain (Vedic compatibility between two people), so the agent knows this compares two birth charts rather than analyzing one. It does not name the sibling tools, but their single-person scope (naksha_chart, naksha_daily) makes the contrast inferable.

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?

Explicit triggering conditions ('kundli milan', 'kundli matching for marriage', 'both birth details are provided') are paired with explicit exclusions ('Do not use for name-only matching or Western synastry'). This is exactly the when/when-not routing an agent needs.

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