APIbase

Get Satellite by International Designator

celestrak.satellite.intdes

Read-onlyIdempotent

Look up satellite orbital elements by international designator (COSPAR ID) when the mission ID is known but the NORAD catalog number is not. Returns element sets for payload, rocket body, and debris.

Instructions

Look up satellite orbital elements using the international designator (COSPAR ID / Harvard designation). Returns orbital element sets for all objects associated with the designator: primary payload (suffix A), rocket body (B), and debris fragments (C onward). Format is YYYY-NNNX where YYYY=launch year, NNN=launch number of year (zero-padded to 3 digits), X=piece letter. Examples: "1998-067A" (ISS ZARYA module launched 1998, 67th launch, primary payload), "1990-037B" (Hubble Space Telescope), "2019-029B" (Starlink batch 1 rocket body). Useful when you know the mission designator but not the NORAD catalog number. Data from US Space Force via CelesTrak.

Input Schema

Name	Required	Description	Default
`intdes`	Yes	International designator (COSPAR ID) for the launch or object. Format: YYYY-NNNX where YYYY is launch year, NNN is launch number of that year (3 digits), and X is the piece letter (A=primary payload). Examples: "1998-067A" (ISS ZARYA module), "1990-037B" (Hubble Space Telescope), "2019-029B" (Starlink batch 1). The suffix letter distinguishes primary payload (A), rocket body (B), debris (C onward).

Output Schema

Name	Required	Description	Default
`error`	No	Present only when the call failed. Includes error code, message, request_id, and any provider-specific extras.
`result`	No	Tool response payload. Shape varies per tool — consult the tool description and inputSchema. May be an object, array, string, or number depending on the upstream provider response.

Schema Changelog

Changes observed during successful MCP inspections.

Addedv2.2.0Oct 29, 2026

TDQS

A4.2/5.0

Behavior4/5

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.

Conciseness4/5

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.

Completeness5/5

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.

Parameters3/5

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.

Purpose5/5

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.

Usage Guidelines4/5

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.

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