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

Annotations only cover safety profile (non-readOnly, non-destructive, closed world); the description adds substantial context beyond that: the exact privacy contract (members see chosen name, usual times, and easy/long run day and distance for two weeks; hard sessions show only as 'hard'; nothing else from Garmin is shared). It also discloses the invite-code format and the default crew name, which an agent would otherwise have no way to know.

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 privacy scope, followed by an itemized Args block that stays close to one line per parameter with no filler. The inline enumeration of six usual_times values makes the block dense, but nothing is redundant.

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 10-parameter, conditionally-branched mutation tool, the description covers the mode switch, per-parameter semantics, defaults, and the privacy consequences of the call. An output schema exists, so return values need not be explained here.

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 10 parameters, so the description must carry the full load and does: every parameter is explained, including the enumerated values for usual_times, the match semantics ('Runs on the same day are matched by these'), and the format hints for club_run_day ('fri') and club_run_time ('HH:MM') and club_run_km (km).

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 ('Join ... or start') and resource (a Daash crew), and immediately defines the data-sharing scope, which distinguishes it cleanly from get_crew, update_crew and leave_crew. An agent can tell what this does 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?

The description makes the join-vs-create branch explicit: supply 'code' to join a friend's crew, or set start_new_crew=True to create one, and it labels the crew/club_run_* params as 'when starting'. It stops short of naming sibling alternatives (get_crew, leave_crew) or stating preconditions such as already being in a crew, so it is clear context without full routing.

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