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

With no annotations provided, the description carries the full burden. It discloses the scope ('this API key can act on'), the FREE cost implication, and the critical constraint that ids cannot be guessed or carried over. It doesn't mention pagination or rate limits, but for a zero-parameter list call the disclosed behavior is quite useful.

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?

Three sentences, each earning its place: what it returns, the cost note, and the critical usage ordering. The most important operational guidance ('Call this FIRST') is front-loaded in the second sentence and the rationale is tight.

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 zero-parameter, no-output-schema tool, the description is nearly complete: it names the resource, the returned fields, the cost, and the session-ordering requirement. It could add pagination or sorting behavior, but 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?

There are zero parameters, so the schema provides no semantics to add. The description compensates by explaining what the returned list contains (id, name, slug, custom domain, page count), which is the relevant semantic context for a parameterless call. Baseline 4 for zero params is appropriate.

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?

The description states a specific verb ('Lists') and resource ('every programmatic-SEO project this API key can act on'), and enumerates the returned fields (id, name, slug, custom domain, page count). It clearly distinguishes this from siblings like seo.project.get and seo.project.create by focusing on listing all accessible projects.

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?

The description explicitly says to call this FIRST in any session and explains why: every other tool needs a projectId from here, and ids cannot be guessed or carried over from another account. This is strong when-to-use guidance that also implies when not to use alternatives (e.g., seo.project.get for a single known project).

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