Vigi-Sky

Nasa Apod

nasa_apod

Read-onlyIdempotent

NASA Astronomy Picture of the Day via Vigi-Sky.

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`apod`	No
`citations`	Yes
`provenance`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedNov 2, 2026
- addedOutput schema / properties / apod / properties / available
```
Added value: +{
+  "type": "boolean"
+}
```
- changedOutput schema / properties / apod / properties / date / type
```
Previous value: -"string"New value: +[
+  "string",
+  "null"
+]
```
Changed1 schema field changedAug 18, 2026
- addedOutput schema / required
```
Added value: +[
+  "citations",
+  "provenance"
+]
```
First observedAug 17, 2026

TDQS

A3.5/5.0

Behavior3/5

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds only the source 'via Vigi-Sky' and no further behavioral context like caching or freshness; with rich annotations, a 3 is appropriate.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Single short sentence, front-loaded with the resource name and source. No wasted words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Output schema exists and annotations are rich, so return values and safety are covered. The description could state whether it returns the current day's APOD only, but for a no-param tool it is nearly complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Zero parameters, so the baseline is 4. The description does not need to explain parameters, and the empty schema is consistent.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

Names the specific resource (NASA Astronomy Picture of the Day) and source (Vigi-Sky), making it distinguishable from siblings like moon or solar. However, it omits an explicit retrieval verb and scope such as whether it returns today's image, so it is clear but not fully specified.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides no guidance on when to use this tool instead of siblings such as tonight_sky, sky_events, or object_lookup. The agent must infer usage from the name alone.

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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