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

Annotations already declare readOnly, idempotent, non-destructive and closed-world (openWorldHint=false). The description reinforces this by calling it a 'pre-built' catalog, i.e. a fixed enumeration, and discloses the return shape (ids + labels), which matters because no output schema exists.

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?

A single front-loaded sentence that names the resource, the payload, and the consuming tool. Every clause earns its place; no filler.

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 no-arg, read-only listing tool with no output schema, the description supplies the essentials: what comes back (ids + labels) and what consumes it (insert_block). Minor gaps remain, such as whether the catalog is static across sites or versioned, but the core need is covered.

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?

Zero parameters, so the baseline is 4; there is no parameter semantics to explain and the description correctly avoids inventing any. Nothing about the empty schema is left ambiguous.

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 (List) and resource (pre-built block catalog), and further narrows scope by noting it is the catalog 'available to insert_block'. An agent can distinguish it from the many other list_* siblings without opening any 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 reference to insert_block implies the workflow (call this first to obtain valid ids, then pass them to insert_block), which is clear usage context. It stops short of an explicit when/when-not statement or naming alternatives like list_templates or list_symbols for other catalogs.

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