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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds genuinely valuable behavioral context beyond that: restricted moves are server-filtered to the caller's visibility, the summary mode truncates to a prose preview with a descriptionTruncated flag, and a campaign-membership auth requirement exists. No contradiction with annotations.

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?

Three sentences, zero waste. The core action and default behavior are front-loaded, the summary-mode behavior is compressed into one semicolon clause (with full detail delegated to the schema), and the visibility filtering and membership requirement each earn their own sentence.

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 2-parameter, non-nested list operation with a full output schema and complete safety annotations, the description covers everything an agent needs: ordering, default vs summary modes, visibility filtering, and the caller prerequisite. Return-value shape is handled by the output schema, and pagination is not a meaningful gap given no pagination parameters exist.

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 100%, so the schema already fully documents both parameters — the detail param description is exceptionally thorough (truncation budget, word-boundary cuts, flag semantics). The description restates the detail behavior only briefly and adds no new syntactic or format information, so the baseline 3 applies.

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 moves grouped under one session' — and clarifies the domain-specific term ('a play-by-email chapter'). The scope is further pinned down by 'in reading order with full bodies by default,' making it easily distinguishable from siblings like play_list_campaign_moves, play_get_move, or play_list_campaign_sessions without opening their schemas.

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?

Provides clear context: this is the tool for listing moves within one session, with a stated prerequisite ('Caller must be a member of the session's campaign') and guidance on choosing summary vs full detail. It stops short of explicitly naming alternatives or exclusions (e.g., 'use play_get_move for a single move'), which the large sibling list would have benefited from.

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