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

Annotations already mark the operation as read-only, idempotent, and non-destructive; the description adds meaningful operational context beyond those annotations: data source (ll.thespacedevs.com), no auth required, a 15-requests/hour shared throttle, and 24-hour caching. This is exactly the kind of behavioral detail that helps an agent set expectations.

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?

Two efficient sentences: the first covers purpose and return content, the second packs in data source, auth, rate limit, and caching. There is no filler and the most decision-relevant information 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?

For a simple optional-parameter read-only search tool with an output schema, the description is complete: it states what is searched, what is returned, where data comes from, whether auth is needed, and the throttling/caching behavior. Nothing required for correct invocation 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 description coverage is 100%, so both parameters are already well documented. The description only reiterates 'by name' and 'optionally filtered by a free-text search,' adding no new semantics; it is also slightly looser than the schema's 'across name/mission/agency fields.'

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 uses a specific verb ('Search') with an explicit resource ('space agencies and commercial launch operators'), names the returned fields (type, country, founding year, description), and clarifies the optional free-text filter. This clearly separates it from sibling tools like launch-library-2.launches.* and launch-library-2.astronauts.search.

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?

Usage is implied by the resource scope — an agent can infer this is for agency lookups — but no alternatives are named and no when-not-to-use conditions are given. It lacks explicit routing guidance relative to sibling launch-library-2 tools such as astronauts.search or launches.detail.

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