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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so safety is covered structurally. The description adds genuinely useful non-annotated context: that it duplicates the <page_context> block (same data, wasted turn) and is redundant before mutations. It doesn't describe the return shape, but for a read-only probe that is minor.

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?

Front-loaded with the core purpose, then the conditions of use, then the warning. Three tight sentences with zero filler; the redundancy warning earns its length by preventing a wasted turn.

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 parameterless, read-only probe with no output schema, the description covers what it returns, when to call it, and when not to. Nothing an agent needs to invoke it correctly 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?

Zero parameters, so the inherited baseline is 4. The description actually names the returned fields (route, entity type/id/name, selection), which compensates for the absent output schema, though that is return-value context rather than parameter guidance.

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+resource ('Returns what the user is looking at') and enumerates the exact payload — route, entity type/id/name, selection — so the agent knows precisely what this retrieves. It is clearly distinguishable from the sibling tools list_capabilities and whoami.

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 explicit trigger conditions ('Use ONLY when they ask what page they are on, or when <page_context> reads "(none …)"'), plus an explicit anti-pattern: never call it when page_context already names an entity, and never before editing/deleting that entity. When-to-use and when-not-to-use are both spelled out.

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