nasa_mars_photos

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

With the readOnlyHint annotation already indicating a safe read operation, the description adds useful domain context by enumerating valid rovers (curiosity, opportunity, spirit) and camera examples. However, it does not disclose the response format, pagination, or any limitations such as rate limits. It goes slightly beyond the annotation but lacks rich behavioral detail.

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 compact and efficient: a single purpose sentence followed by two short enumerations. It is front-loaded with the main action ('Get Mars Rover photos') and provides necessary enumeration without fluff. Every sentence earns its place.

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?

Given the tool's simplicity, the description covers the essential purpose and parameter options. The absence of an output schema means it could have described what the response contains (e.g., photo URLs), but the phrase 'Get photos' implies it returns photos. With complete schema coverage and readOnlyHint, it is sufficiently complete for an agent to invoke it correctly.

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 already has 100% coverage with descriptions for all four parameters. The description repeats some of this information (e.g., sol meaning 'Mars day' and the list of cameras) but adds no new meaning beyond the schema. The only slight addition is the phrase 'use sol OR earth_date' implied in the first sentence, though the schema also states this.

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's function: 'Get Mars Rover photos by sol (Mars day) or Earth date.' It specifies the exact resource (Mars Rover photos) and the filtering dimensions (sol/date), with a specific verb ('Get'). It also lists the relevant rovers and cameras, distinguishing it from other NASA tools like nasa_image_search or nasa_neo.

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 clear context for when to use the tool: whenever Mars Rover photos are needed by sol or Earth date. It does not explicitly name alternative tools or exclusions, but the purpose is so specific that an agent can infer when to use it. The inclusion of available rovers and cameras implicitly defines the scope of use.

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