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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds real behavioral context beyond that: the auto-fallback behavior for quadrant systems above 66.5° latitude, plus cost (10 credits) and endpoint. It does not discuss precision/rounding behavior or any rate limits, but the fallback disclosure is meaningful value-add.

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?

Front-loaded with the purpose and outputs, followed by supported systems and the fallback caveat. The bracketed metadata block (group, endpoint, required, cost) is compact and scannable. Nothing is wasted, though the supported-systems list drifts slightly toward an unstructured enumeration.

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 described, and the annotations cover the safety profile. However, for a 15-parameter tool with only 33% schema coverage, the agent is left guessing at several optional inputs (cosmogram, zodiacType, precision, fields). Adequate at the surface level but incomplete on configuration.

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%, so the description should compensate, and it largely does not. It names house systems in prose (Placidus, Koch, Campanus...) which partly decodes the opaque houseSystem letter enum, but several parameters (city, name, cosmogram, zodiacType, ayanamsaId) remain undocumented in both places. Required inputs are listed, matching the schema, adding no new semantics.

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 states a specific verb and resource ('Standalone house calculation') and enumerates exactly what is produced (12 cusps + ascendant + MC + ARMC + vertex + co-asc + polar-asc), which is far more specific than the title 'House Cusps'. 'Standalone' implicitly separates it from full-chart siblings like astroway_western_chart, though no sibling is named explicitly.

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 context is only implied by the word 'Standalone' — there is no explicit 'use this when you need only houses, use western_chart when you need planets too' routing. The one genuine usage caveat given is the auto-fallback warning at |lat|>66.5°, which tells the agent when results may degrade, but when-to-use vs alternatives 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.