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

Annotations already declare a safe read (readOnlyHint, idempotentHint, destructiveHint=false), and the description adds meaningful behavior on top: newest-first ordering, no paging, empty-list meaning, and an auth-dependent error asking the customer to sign in. That exceeds the bar set by the 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?

Dense but every clause earns its place: trigger, parameter semantics, return shape, failure mode, and sibling routing, with the usage condition front-loaded. No filler sentences.

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 the description need not detail returns, yet it still characterizes the key fields and the empty-list and unauthenticated cases. Combined with annotations, an agent has everything needed to call this 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 already documents the 1-20 bounds and default, so the baseline is 3; the description goes further by explaining the semantic intent of limit ('most recent, newest first') and the reason not to raise it (no paging). It stops short of adding format details but is clearly above baseline.

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 ('recent teas.co.uk orders' for a signed-in customer) and scopes it to the caller's own orders, which cleanly separates it from the many sibling order/product tools. An agent can identify this tool's job 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 the triggering condition ('when a signed in customer asks about their recent orders'), the constraint on when to raise limit, and explicit routing to alternatives: track_order for tracking, reorder for repurchase, start_return for returns. Nothing is left to inference.

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