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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds only a list of returned fields, which is already encoded in the output schema, and says nothing about auth, rate limits, or whether url/slug must point at a canonical author page.

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?

A single efficient sentence with the resource front-loaded. Nothing is wasted, though it spends words enumerating fields that the output schema already defines.

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?

An output schema exists, so return values need not be explained, yet the description duplicates them while leaving both input parameters undocumented and offering no usage context. For a lookup tool with two ambiguous optional identifiers, this is under-specified.

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% for both url and slug, and the description never mentions either parameter. With zero documented and zero required parameters, the agent has no guidance on which identifier to supply or what format each expects.

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 ('One Mirror author's public profile') and enumerates the fields returned, so the agent knows this retrieves an author entity rather than an article. It doesn't explicitly distinguish itself from mirror_article/mirror_headlines, but the resource noun makes the distinction inferable.

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?

There is no when-to-use guidance, no prerequisites, and no reference to any alternative tool. The agent must infer from the name alone when this is the right call versus mirror_article or mirror_sections.

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