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

Goes well beyond the annotations: discloses this is a live API call, that it runs under the caller's OWN OAuth token rather than the operator key, that it is free (no credits), and provides a behavioral warning to check `requiresReconnect` before interpreting an empty `sites` list. This is exactly the kind of auth, cost, and failure-mode context annotations cannot convey.

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 statement, then layered context. Slightly dense with parenthetical asides, but every clause carries information an agent needs (auth scope, free cost, reconnect caveat) rather than filler.

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?

Given a single-parameter, no-output-schema read tool, the description still conveys the return shape (`sites` list), the empty-list edge case, and the auth/cost profile. Nothing needed to invoke or interpret the result 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?

Only one parameter and schema description coverage is 100%, so the schema already documents projectId fully (including its provenance from list_projects). The description adds nothing extra about the parameter, so the baseline 3 applies.

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 (every site accessible to the caller's Bing Webmaster OAuth grant) and names the underlying API call GetUserSites. It also positions itself relative to the sibling set_bing_site, so an agent can distinguish it without opening schemas.

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?

Explains the when: it is the data source for picking which site to bind to a project, and explicitly points to set_bing_site as the follow-up action. There is no explicit when-not, but the routing context is clear and unambiguous.

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