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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely useful behavior beyond them: results are sourced from 'last reported location' and ordered by distance. It omits pagination/limits and doesn't explain what happens if no location is known, but with strong annotation coverage this is a solid add.

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 short sentences, front-loaded with the user-facing trigger followed by the mechanics; every sentence earns its place. Minor awkwardness from the nested quotation but no wasted content.

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?

An output schema exists, so return values needn't be described, and annotations cover safety. The description supplies the key context an agent needs (proximity source, distance ordering, trigger scenario); only edge cases like missing-location behavior are absent.

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?

Schema description coverage is 100% and radius_meters documents its range and default (10 to 5000, default 200). The description adds nothing about the radius parameter, so the schema carries the full load and baseline 3 applies.

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 (lists) and a well-scoped resource: contacts with known addresses near their last reported location, ordered by distance. This distinguishes it from the generic contacts.list and places.list siblings without naming them explicitly, which keeps it just short of a 5.

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?

Provides a concrete trigger scenario ('when the user wonders who is nearby, like "anyone I know around here?"'), which is a clear when-to-use signal. It does not explicitly name alternatives (e.g., contacts.list for non-proximity lookups) or state when-not-to-use, so it falls short of a 5.

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