get_astronomy_picture

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

Without annotations, the description adequately discloses that the tool returns the APOD image and explanation, and that behaviors change based on parameters. No mention of destructive actions or permissions, which is acceptable for a read-only tool.

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 a clear structure: brief intro, parameterless behavior, then optional parameters. Every sentence is informative and no redundant wording.

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?

While the description covers purpose and parameters, it lacks details about the return value structure (e.g., fields like URL, title, explanation). Given no output schema, this omission leaves the agent uncertain about what data to expect.

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 input schema only provides types and titles (0% coverage), but the description adds critical meaning: date format YYYY-MM-DD and count range 1-100. This fully compensates for the schema gaps.

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 'Astronomy Picture of the Day (APOD) abrufen' and explains three distinct usage modes (no param, date, count), distinguishing it from sibling tools like get_asteroid_details or get_mars_rover_photos.

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 explicitly outlines when to use each parameter (today, specific day, random images), but does not provide guidance on when not to use this tool or compare with alternatives.

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