astronomy_picture_of_the_day

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

No annotations are provided, so the description carries the burden of behavioral disclosure. It indicates a fetch operation (read-only), and mentions rate limit implications, but does not detail side effects or response structure. The existence of an output schema mitigates the need for return format details.

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 concise with two sentences: the first states the core purpose, and the second provides authentication tips. No extraneous information, and the key action is front-loaded.

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 tool is simple with one optional parameter, and an output schema exists. The description covers the main behavior and default behavior (today if no date). It could explicitly state that omitting 'date' returns today's picture, but this is implied. Overall, it is sufficiently complete for this low-complexity tool.

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 0%, so the description must add meaning to the 'date' parameter. It implies the parameter accepts a date string or null for today, but does not specify the date format (e.g., YYYY-MM-DD). This provides partial clarity but lacks completeness.

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 fetches NASA's Astronomy Picture of the Day for a specific date or today. The verb 'Fetch' and resource 'APOD' are specific, and the tool is distinct from siblings like 'get_ephemeris' or 'resolve_object' which serve different purposes.

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 mentions using a public DEMO_KEY and configuring a NASA key for higher rate limits, but provides no guidance on when to use this tool versus alternatives. No exclusions or context about other tools are given.

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