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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds one genuinely useful behavioral fact — the list is implicitly filtered to places that actually have peptide providers, not all places — but says nothing about ordering, completeness, or return shape.

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 scoping qualifier ('that have peptide providers') is placed at the end where it does the most work and nothing is repeated.

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-parameter, no-output-schema listing tool, the description is nearly sufficient: it states what is enumerated and under what implicit filter. It could mention whether results are grouped hierarchically (country > region > city) or flat, which matters for a three-level entity list.

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 per the baseline a 4 applies. There is nothing for the description to clarify beyond what the empty schema already communicates.

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 supplies a specific verb (List) and disambiguates the vague resource name 'places' by naming the actual entities returned: countries, regions and cities. It doesn't explicitly differentiate itself from siblings like list_categories or list_sources, but the peptide-provider scope makes the domain 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?

There is no guidance on when to call this versus the sibling listing tools (list_categories, list_sources, get_listing). Usage is only implied by the name and the one-sentence purpose; no prerequisites, exclusions, or alternatives are stated.

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