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

Annotations already declare readOnlyHint/idempotent/non-destructive, so the safety bar is lower; the description adds real context beyond that — the paid-site gating constraint, the correct downstream tool, and the instruction that listed pages are 'to study, not copy'. It stops short of saying what the response looks like on a paid-tier failure or how large the brief is, but the behavioral picture is substantially enriched.

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?

Purpose is front-loaded in the first clause, followed by a compact enumeration and then two short operational sentences. The middle list is dense but each item is a distinct content guarantee an agent would otherwise have to discover; only minor tightening is possible.

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?

An output schema exists, so return values need not be explained; the description instead covers the things the schema cannot — repo context, follow-up tool, default argument, and paid-tier restriction. Nothing an agent needs before calling is missing.

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%, so both parameters are already fully documented, including the move-id format and site identifier forms. The description only echoes the default ('the top move') and adds no format or edge-case detail beyond the schema — baseline 3.

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?

The description names a concrete verb and resource — 'One move of a site's plan as a complete, self-contained brief for a coding agent' — and then enumerates exactly what the brief contains (goal, target questions, rivals, pages read, page anatomy, prohibitions, measurement). An agent can tell this apart from action_plan or briefing without opening either 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?

It says where to run it ('In a coding session opened on the site's repo'), what to do afterwards ('implement it, then call mark_move_done'), the default behavior ('Default: the top move'), and a hard eligibility gate ('Paid sites only, as in the app'). That is explicit use, follow-up, default, and restriction in one pass.

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