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

Annotations already declare the write/destructive/idempotent profile, so the bar is lower; the description usefully adds the account-consent requirement and that it returns 'source/freshness metadata'. However, it never says whether omitted fields are preserved or overwritten, which is the key behavioral question for a partial-update mutation.

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 purpose is front-loaded and the total length is short, but the second block (units and direction convention) is boilerplate irrelevant to this tool's numeric parameters, so not every sentence earns its place.

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?

With no output schema, mentioning the return of 'data and source/freshness metadata' is useful, and the consent requirement is relevant context. Still, for a destructive nested-schema mutation, the description leaves field-level semantics and update semantics under-specified.

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 0% across a nested body with nine updatable fields (lat, lon, kind, name, sort, notes, boatId, spotId, activity), and the description documents only 'name'. The trailing units line ('ft, kt, s, F, mi; directions FROM') does not map to any parameter here and reads as boilerplate, so it does not compensate for the gap.

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?

Specific verb+resource: 'Update specified saved-place fields, including name to rename a saved pin.' It is clearly distinguishable from update_my_trip and update_my_settings, though it never explicitly contrasts with save_my_place (create) or delete_my_place (remove).

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?

It states a prerequisite ('Requires your Gillby account and explicit account consent') and implies partial-update semantics via 'specified ... fields', but gives no when-to-use guidance relative to save_my_place/delete_my_place or any exclusions. Usage is inferable rather than stated.

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