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

Without annotations, the description carries the full burden of behavioral disclosure. It thoroughly details the return structure, including nested objects like Biome, Hazard, and Statistics, and mentions conditional information (e.g., event info if active). It also states the requirement and limit on planetindices. However, it does not discuss error behavior, rate limits, or side effects, though the tool appears to be a read-only fetch.

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?

The description is front-loaded with the main purpose, followed by requirements and a comprehensive output list. Every piece of information is relevant given the tool's complexity, but the entire description is a single dense paragraph. It is not as concise as it could be with bullet points or shorter sentences, yet it earns its place by documenting many return fields.

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?

The description is exceptionally thorough for a tool with no output schema. It enumerates all return fields, including nested structures and conditional sections, and provides parameter constraints. For the tool's complexity, this description leaves little ambiguity about what the agent will receive, making it contextually complete.

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?

The schema description only says 'A list of planet indices to get detailed information for.' The tool description adds practical constraints: 'maximum of 5' and implies a minimum of 1 ('one or more planets'). This enriches the parameter semantics beyond the schema, even though schema coverage is 100%.

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 clearly states the tool's function: 'Fetch detailed information about one or more planets by providing their planet index/indices.' It specifies the resource (planet details), the verb (fetch), and the input (planet indices), which distinguishes it from siblings like get_all_planets that likely provide a list without full detail.

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 implies usage by stating the required parameter and the maximum of 5 indices, but it does not explicitly contrast with alternative tools or provide exclusion criteria. For example, it does not say 'use get_all_planets for a simple list' or 'use this only when you need detailed stats'. The guidance is inferred from the tool name and purpose rather than explicit.

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