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

Annotations already cover read-only, idempotent, closed-world and non-destructive behavior, so the description's added value is the 'Free' cost note and the ordering semantics ('first = primary, the default') that govern how returned niches should be interpreted. That is meaningful context beyond the annotations, though it does not discuss freshness or whether a profile can be absent.

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?

Two compact fragments, front-loaded with the resource and its contents, then the action guidance. Every clause carries information, though the parenthetical '(first = primary, the default)' is densely packed and slightly awkward to parse on first read.

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 and no parameters, the description carries the full burden of describing the response, and it does so by naming each returned element. An agent knows both what it gets back and why to call it before asking the user.

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?

The tool takes no parameters, so there is nothing for the description to disambiguate; baseline for a zero-parameter schema applies. The description instead spends its space on what the call returns, which is the useful place to spend it.

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 resource (the user's saved profile) and enumerates its contents: ordered niches with primary default, pool status and price, own accounts, niche policy. This distinguishes it from list-style siblings like niches_list and from account/me. It stops short of explicitly saying how it differs from the near-neighbour 'me' tool.

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 an explicit precondition: 'read it before asking the niche', which tells the agent to consult stored preferences rather than prompt the user. It also flags the call as 'Free', removing cost concerns as a barrier. No exclusions or named alternatives (e.g. when to prefer 'me' or 'account') are provided.

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