health_sync

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

With no annotations, the description carries the full behavioral burden and does well: it discloses incremental-only fetching, first-sync semantics, that 'days' is ignored on subsequent syncs, that 'since' overrides both incremental resume and 'days', and that since..until performs an upsert over exactly that window. It does not mention authentication requirements, rate limits, or error/timeout behavior, which leaves a modest gap for a network-bound mutation of the local cache.

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 purpose, then behavior, then parameters, then exclusions. The only bulk is the enumerated data_types list, which is necessary because the schema has no enum, so it earns its place. Slightly verbose but nothing is wasted.

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 4-parameter write-to-cache tool with no annotations, the description covers purpose, sequencing relative to siblings, incremental semantics, override precedence, and the full option set for data_types. An output schema exists, so not detailing the per-type return payload is appropriate.

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%, so the description must compensate entirely, and it does: all four parameters are documented with formats (YYYY-MM-DD), defaults, comma-separated syntax, the full list of 23 data_types options, and the precedence rules between days/since/until. This adds far more meaning than the bare-typed schema provides.

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+resource ('Sync health data to the local cache') and immediately clarifies the mechanism ('Fetches data from the Google Health API and stores it in SQLite'). It clearly distinguishes itself from the health_get_* siblings by declaring it is a precondition rather than a query tool.

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 explicit sequencing guidance ('Run this before using other health_get_* tools') and an explicit exclusion ('Not for querying data - use health_get_heart_rate, health_get_activity, health_get_sleep, etc. instead'). It also explains when to use the since/until parameters (backfill, gap repair) vs. the default incremental path.

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