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

Annotations only declare a non-read-only write; the description goes well beyond by disclosing the exact persistent effects (profiles.location + polaris fields), the location_visits row written, that get_location_context will then return is_current, the defaults for set_home and check_in, the fact that GPS is not invented, plus cost ($0.10) and API-key requirement.

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?

Front-loaded with the mutation intent and dense but relevant clauses; the conditional defaults and the 'does not invent GPS' caveat are placed near the params they govern. Slightly long, but nearly every clause carries operational information.

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 need not be explained, and the description covers mutation semantics, defaults, and preconditions. Completeness is strong for a 12-param tool, though idempotency/request_id parameters are left to the schema.

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?

With only 42% schema coverage, the description compensates meaningfully: it gives a format example for location ('The Madeira, Singapore'), clarifies city+country usage, and explains place/venue and the lat/lon trigger for check-in along with set_home/check_in defaults. Minor params (address, request_id, idempotency_key) remain unspecified.

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 (MUTATES) and resource (where the user is now), naming the exact fields touched (profiles.location, polaris current_city/country). It distinguishes itself from the many place/location siblings by tying the write to location_visits and get_location_context's is_current, so an agent can differentiate it without opening the 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?

Gives clear invocation context: pass location and/or city+country, plus optional place/venue+lat/lon to record a check-in. It explains default behavior (set_home, check_in) so the agent knows what happens when omitted. It stops short of explicitly naming alternative tools or when-not-to-use cases.

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