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

Goes well beyond the readOnly/idempotent annotations by disclosing server-side permission filtering (players see only moves they're listed on; GM and Admin Mode admins see all) and the read-authorization rule for the campaign. That is exactly the behavioral context annotations cannot carry.

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?

A single dense paragraph that is front-loaded with the core purpose before parameter details; every sentence carries information. It is on the long side and packs many semicolons, but nothing is filler.

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 an output schema present, return-value documentation isn't required, yet the description still explains the summary vs full shapes and the truncation flag. Permissions, defaults, and sorting are all covered, so an agent has everything needed to call it correctly.

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 coverage is 100% and the parameter descriptions are already detailed, so the description largely restates order/detail/children/limit semantics. It adds framing around the summary shape's descriptionTruncated flag and word-boundary cut, but that content is also present in the schema, so a baseline 3 is appropriate.

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 and resource ('List the play-by-email moves of one campaign — the move feed') and distinguishes itself from siblings like play_list_session_moves by scoping to campaign moves. An agent can identify what the tool returns 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 concrete guidance on parameter-driven use cases ('pass order: asc for reading order', 'pass children: true when you need every move, e.g. to pick an append target'). It does not name sibling alternatives such as play_get_move or play_list_session_moves for related reads, so routing is left partly to inference.

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