Search Instrument Hosts

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

No annotations are provided, so the description carries the burden; 'Search' implies a safe read, but nothing is said about result limits, ordering, or whether the call can fail on bad input. It adds useful context via the example URN and by declaring what an instrument host is, but not richer behavioral traits.

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?

Purpose and definition are front-loaded, and the usage sentence comes last. It is slightly repetitive, restating 'spacecraft, rovers, telescopes' twice and re-explaining 'platforms that carry instruments'.

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?

An output schema exists, so return values need not be explained, and 100% schema coverage means parameters are handled. The description supplies the domain concept plus example URN, which is enough for an agent to use this correctly; only explicit sibling routing is missing.

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 coverage is 100%, so all three parameters (limit, keywords, instrument_host_type) are already documented in the schema, including format hints. The description adds no parameter-level detail beyond that baseline.

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?

States a specific verb and resource ('Search PDS Context products that are Instrument Hosts') and then defines the resource precisely, including an example URN. The framing 'platforms that carry scientific instruments' implicitly separates it from the sibling search_instruments, so an agent can pick correctly without opening a schema.

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 final sentence gives clear positive guidance ('Use for queries about specific spacecraft, rovers, or platforms that carry instruments') and the keywords examples ('mars rover', 'voyager spacecraft') reinforce the intended context. There are no explicit exclusions or named alternatives, so it falls short of a 5.

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