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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety and scope are covered. The description adds the useful detail that each result carries a one-line summary, but says nothing about ordering, completeness of the list, or how many modules appear, which are the remaining behaviors an agent might need.

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 with no filler: the verb and resource come first and the return-content clause follows. Nothing is redundant or restated from the title.

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 zero-parameter read-only listing tool with no output schema, the description covers what is returned at a high level (one-line descriptions per module). Completeness is only slightly short of ideal because it doesn't say whether the listing is exhaustive or ordered, but nothing essential to making the call 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?

The tool takes zero parameters, so there is no parameter meaning to convey and the schema carries no burden. A baseline of 4 is appropriate for a no-arg tool whose inputs need no explanation.

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 verb and resource ('List the playbook modules') and adds what each entry contains ('a one-line description of each'), so the agent knows exactly what the call yields. It does not explicitly contrast with the sibling get_module, but 'modules' (plural) versus the singular sibling name makes the distinction reasonably clear.

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 only implied: the discovery-then-detail pattern with get_module can be inferred from the one-line summaries, but the description never says when to call this versus get_module or whether it is a safe first step. No exclusions or prerequisites are stated.

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