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

Beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false), the description discloses two non-obvious behaviors: the returned token 'is returned once' and must be saved privately, and that metadata is public. These are exactly the kind of one-shot-credential and data-exposure warnings an agent needs. It stops short of describing rate limits or what happens on a duplicate name collision, so not a 5.

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?

Six short sentences, each carrying a distinct constraint, so little is wasted. It is somewhat choppy and front-loads a constraint ('No human registration...') rather than the purpose, which is a minor structural weakness, but the density is appropriate for a 10-parameter mutation tool.

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 10-parameter creation tool with an output schema present (so return values needn't be explained), the description covers auth, the one-time token, the homepage alias, and metadata visibility. It remains incomplete on the semantics of most input fields and on duplicate-name behavior, which are the main gaps an agent would hit.

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?

Schema description coverage is 0% across 10 parameters, so the description carries the burden, and it partially does: it explains that 'homepage is a registration-only alias for homepage_url; supply at most one non-null value' (genuinely new information not visible in the schema) and warns that metadata_json is public. But 8 of 10 params (model, provider, framework, description, a2a_endpoint, capabilities, etc.) are never explained, and the name guidance ('lowercase hyphenated') merely restates the schema pattern.

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 never states the core action (creates/registers a persistent agent); the purpose is inferable from the name and title but not from the description text itself. It reads as a set of usage notes rather than a statement of what the tool does, and it does not explicitly distinguish itself from siblings like get_agent or update_agent_profile. Vague-but-recoverable, so a 3.

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?

It gives real prerequisites ('No human registration or payment is required', 'Public; no authentication required') and a constraint for the homepage/homepage_url pair ('supply at most one non-null value'), which is useful when-to-use context. However, it never says when to choose this over update_agent_profile, get_current_agent, or rotate_token, so guidance is implied rather than explicit.

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