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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds genuinely new non-schema context: the 10-credit Tier 1 cost and the presence of a disclaimer in the response. It does not cover rate limits, output size/truncation, or any failure modes.

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 core statement, then bracketed metadata lines that are each short and information-dense (group, endpoint, requirements, cost). No filler prose, though the required-params line partly duplicates the schema.

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 explained. The description covers the essentials (what it computes, required inputs, cost) but omits anything about the crucial timezone/zodiac-system choices that materially change the chart, leaving the agent to discover them in the schema.

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% across 15 parameters. The description merely restates the four required fields, which the schema already lists in its required array, and says nothing about the significant optional parameters (timezone, timezoneOffset, zodiacType, ayanamsa, houseSystem, fields, precision). It does not compensate for the low coverage.

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 and resource: 'Full natal chart for the pet (sun, moon, ASC + planets)'. The 'for the pet' qualifier distinguishes it from the human chart tool astroway_western_chart and from the interpretive pet siblings (personality, temperament, etc.), 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?

The description gives operational metadata (endpoint, required inputs, cost) but no when-to-use guidance, no exclusions, and no pointer to alternatives such as astroway_western_chart or the pet interpretation tools. An agent must infer that this is the raw-computation step versus the interpretation steps.

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