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

With no annotations, the description carries the full burden. It describes the return fields (name, has_audio, duration_ms, source, script_text) and their semantic meaning, especially the has_audio flag and its impact on dropping. It does not explicitly state that the operation is read-only or non-destructive, but as a list operation this is implied. It also lacks mention of pagination or limits, but for a simple list that is acceptable.

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?

The description is two sentences with no fluff. The first sentence states the purpose and lists key fields; the second gives actionable usage guidance. It is front-loaded with the core action and efficiently provides all necessary context.

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 parameterless list tool without an output schema, the description fully covers what an agent needs: it lists the returned fields, explains the has_audio caveat, and tells when to call it relative to voicemail_drops_drop. There are no hidden requirements or missing details that would impede correct invocation.

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 has zero parameters and the schema is empty (100% coverage), so the description does not need to explain parameters. The baseline for 0 params is 4, and the description adds no param-specific info but instead enriches the output semantics, which is appropriate here.

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 clearly states 'List the user's saved voicemail drops' with a specific verb and resource. It further distinguishes itself from siblings by noting it should be called before voicemail_drops_drop, making the purpose and differentiation unambiguous.

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 description explicitly says 'Call this before voicemail_drops_drop so you know which drop_id to use,' providing a clear usage condition and relationship to a sibling tool. It also explains the has_audio flag and its implication for drop usability, guiding when the list is relevant.

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