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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds real behavioral context beyond them: deterministic reasoning over pre-calculated chart facts rather than runtime retrieval, a complete explanation trace as output, and no annual timing. It does not discuss cost, latency, or failure modes on bad birth data.

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 dense sentences that front-load the primary action and scope, with the 'annual timing is not implied' caveat placed last where it reads as a qualifier. No padding, though the list of chart factors is jargon-heavy and slightly slows the read.

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 the return values need not be re-explained (and the 'explanation trace' note is a bonus). However, for a 10-parameter tool with two mutually exclusive geolocation paths and 30% schema coverage, the description leaves the input contract under-specified for correct invocation.

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 only 30% across 10 parameters, so the description carries a heavy burden, yet it adds meaning only for 'topic' via 'topic-aware'. It says nothing about the anyOf location contract (place vs latitude/longitude/timezone), timezoneOffset fallback, or birthTimeAccuracyMinutes, which are exactly the parameters an agent could get wrong.

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 concrete verb and resource: 'Calculates a topic-aware Lal Kitab natal prediction and remedy plan', and names the constitutive inputs (fixed houses, friendship/enmity, dormancy, eclipse, birth-period). It carves out a distinct methodology ('without searching the corpus at runtime'), which separates it from the retrieval-oriented siblings, though it never names analyze_lal_kitab or analyze_lal_kitab_remedies directly.

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?

'Annual timing is not implied' is an explicit when-not boundary, and the no-corpus-search clause implicitly routes source lookups elsewhere. But with highly overlapping siblings like analyze_lal_kitab, analyze_lal_kitab_remedies and explore_lal_kitab_sources, no alternative is named and the choice between them is left to inference.

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