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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, so the bar is lowered. The description adds real value beyond them by bounding scope (no prediction prose, no annual-chart emulation) and stating what is actually returned (source locators per planet-house section) — a no-annotation schema could not convey 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?

Two sentences, zero filler, with the core transformation front-loaded before the scope limitations. Both the negative scope statement and the sibling pointer earn their place by preventing misfires.

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 need not be re-explained, and the read-only annotations cover the safety profile. The one remaining gap is the input contract — the agent gets no prose about the dual place/coordinate requirement, leaving a fairly complex 9-parameter anyOf schema to speak entirely for itself.

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 only 33% (3 of 9 params), and the description supplies no parameter guidance at all — no date/time format, no explanation of the place-vs-latitude/longitude/timezone anyOf branch, no note on the birthTimeAccuracyMinutes default. With low coverage the description was expected to compensate and does not.

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+resource transformation (natal placements -> Lal Kitab fixed houses) and names the concrete deliverable (source locators for all nine planet-house sections). It also explicitly excludes two adjacent capabilities (prediction prose, annual-chart emulation), which sharply distinguishes it from siblings like analyze_house and analyze_lal_kitab_remedies.

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?

The description routes the agent away from this tool for remedies, naming analyze_lal_kitab_remedies and reason_lal_kitab as the correct destinations, and rules out prediction/annual work. It stops short of stating positive preconditions (e.g. that chart placements must already be verified/calculated) or naming the tool that produces those verified placements.

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