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

Annotations already establish this as a safe, read-only, idempotent operation, so the description's job is lighter. It adds meaningful behavioral detail beyond annotations by disclosing that the query returns orbital element sets for all objects matching a designator—primary payload, rocket body, and debris—and by citing the US Space Force/CelesTrak data source. No contradictions with the annotations were found.

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 purpose, then return scope, format, examples, and usage context. It is slightly longer than strictly necessary because it repeats format details also present in the schema, but every sentence carries useful information and the examples earn their place by disambiguating the designator format.

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?

For a single-parameter, read-only lookup tool with annotations for safety and an output schema available, the description is complete: it explains the keying convention, return scope, when to choose this tool, and data provenance. Nothing an agent needs to select or invoke the tool correctly is missing.

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 already provides 100% coverage of the single required parameter, including format and examples, so the baseline is 3. The description adds slight enrichment with zero-padding emphasis, worked examples, and piece-letter decoding, but it does not introduce meaningfully new semantic information beyond what the schema supplies.

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 uses a specific verb ('Look up') and resource ('satellite orbital elements') keyed by the international designator, and clearly distinguishes this from NORAD-based lookups by saying it is useful when 'you know the mission designator but not the NORAD catalog number.' It also states what will be returned, including the full scope of associated objects, making the tool's purpose unmistakable.

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 explicit selection context: use this when the caller knows the international designator rather than the NORAD catalog number. It does not name the sibling alternatives directly, but the phrase 'but not the NORAD catalog number' clearly sets the boundary against lookups keyed by NORAD ID, which is enough practical guidance.

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