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

Annotations only give the flags (readOnlyHint=false, idempotentHint=false, destructiveHint=false); the description goes further by explaining WHY non-idempotency matters — 'The code works once; the token is what stays valid.' That is exactly the retry behavior an agent needs to know. It leaves failure modes (expired or already-used code) unstated.

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 short sentences, front-loaded with the action and the required input, then the return value, then the lifecycle constraint. No sentence is redundant and nothing is buried.

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 no output schema, the description carries the burden of explaining the return value and does so ('a session token that every other tool takes'). For a single-parameter tool this is nearly sufficient, though it omits what an agent should expect if the code is invalid or the token later expires.

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 the baseline is 3, but the description adds a concrete format example ('K7M4-P2Q9') and provenance ('under the Connect MCP button') that the schema's 'eight-character pairing code shown on the Motion page' does not convey as precisely.

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+resource ('pairs this agent with a Motion browser tab') and immediately scopes it with the exact input ('eight-character code the user sees under the Connect MCP button'). It is clearly distinct from every sibling, which all operate on compositions/media/playback rather than establishing the session.

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?

'Returns a session token that every other tool takes' tells the agent this is the prerequisite step before any sibling tool, which is strong ordering guidance. It does not address the sibling create_session or explain what to do when pairing is not needed, so it stops short of explicit when-not/alternatives.

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