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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, and the description's "Read-only. Cannot spend money." largely restates that safety profile. The genuinely additive part is the return-shape disclosure (project_id, domain/draft counts, unfiled verified domains), though ordering and completeness of the listing are 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?

Front-loads what is returned, then the usage trigger, then the safety note in three compact sentences with no filler. The read-only sentence is near-redundant with annotations, which keeps it from a 5.

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?

Zero parameters and no output schema, so the description carries the return-value burden and does so by naming the fields returned. An agent has everything needed to call this and interpret the result.

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 zero parameters and the schema is an empty object, so there is nothing for the description to disambiguate. Baseline 4 applies; no parameter semantics gap exists.

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?

Uses a specific verb and resource ("Lists the projects this account owns or operates") and goes further by enumerating the payload: each project_id plus domain and draft counts, and a count of unassigned verified domains. That level of specificity cleanly separates it from sibling readers like list_domains and list_drafts.

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?

"For when the user refers to a project, or wants a budget or finance readout, and its project_id is not known yet" gives a concrete trigger and a resolution use case. It stops short of naming alternatives (e.g. get_finance once the id is known), so it falls just short of the top band.

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