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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the bar is lower. The description adds genuine behavioral context beyond them: the result documents the evidentiary basis for answers drawn from the register, which tells the agent this is a provenance/metadata call rather than a data call. Return format and size are still unspecified.

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 sentences, no filler, and the core scope statement ('how many launches are on record, since when, from which venues, and what is free versus licensed') is front-loaded. Every clause earns its place by listing a distinct dimension of the coverage data.

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?

With no output schema, the description carries the burden of describing what comes back, and it does so at a high level by enumerating the coverage dimensions. It stops short of describing the result's structure or units, so an agent knows the content but not the shape — a modest gap for a zero-parameter read 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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description does not need to, and does not attempt to, explain inputs.

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 names a specific resource — the register's own coverage figures — and enumerates what those figures cover (count of launches, date range, venues, free vs licensed). That is enough to separate it from lookup_launch and search_ticker_or_name, which retrieve individual records rather than register-level metadata, though the differentiation is implicit rather than stated.

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 rather than specified: 'The result states the basis for any answer drawn from the register' hints that this should be consulted to establish provenance, but there is no explicit statement of when to call it, when not to, or which sibling to prefer for record-level queries. An agent can infer the role but is not told the condition that selects it.

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