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

Annotations only declare a non-read-only, non-destructive, closed-world write; the description adds genuinely non-obvious behavior - that on a partner-synced boat the hold propagates to that partner and, with X-Lock on, to the other partner - plus a statement of what is returned. It stops short of covering conflict/overwrite handling or auth needs, so not a 5.

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 tightly packed sentences with the core action front-loaded and zero filler; the propagation caveat and return note each earn their 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?

No output schema, but the description states the return shape ('the stored block and how each hold went') and covers the multi-system hold behavior, which is the main complexity risk. Remaining gaps - overwrite/conflict behavior, timezone handling of the date fields, permission requirements - keep it from a 5.

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 schema coverage at 60%, the description must compensate for the undocumented parameters, but it never mentions boat_id, start_at/end_at semantics, notes, or reason. Only 'dates' and 'boat' are implied, and the schema already carries the YYYY-MM-DD format and list_boats hint.

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?

Names a specific verb (block dates) and resource (one of the operator's boats) and states the effect ('so they cannot be booked'), which is enough to separate it from the counter-tool remove_block and from calendar/pricing tools in the sibling list.

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?

Usage is only implied: an agent can infer you call this to make dates unbookable, and the partner/X-Lock sentences hint at when side effects occur, but there is no explicit when-to-use, no alternative named (e.g. remove_block for reversing), and no stated prerequisites such as required permissions.

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