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

Adds substantial behavior beyond the annotations: the scan is asynchronous and cached ("one page per call, kept 15 minutes; call again with the same arguments until complete"), which explains the non-idempotent polling pattern the annotations only hint at. It also discloses that passing url narrows output to what the existing page is missing. This is exactly the operational context an agent needs before invoking.

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 purpose and dense throughout, with the polling instruction parenthetically embedded where it is needed. It spends a long clause enumerating return values that an output schema already covers, which is mild redundancy, but no sentence is 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?

For a 4-parameter tool with an output schema, the description covers prerequisites (competitor URLs), async completion semantics, and the two optional-parameter branches. Nothing an agent needs to call it correctly is missing; the output enumeration is redundant but harmless.

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 coverage is 100%, so the baseline is 3, but the description adds meaning the schema does not: url means "improving an existing page" and changes the result to only missing items, and audit_id must come from a finished site audit and unlocks internal-link suggestions. The competitors count (1 to 3) is restated rather than expanded.

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 and artifact ("Build a writing brief") scoped to a search term derived from ranking pages. It clearly distinguishes this from sibling audit/check tools by naming its inputs (competitor URLs) and its output class (subtopics, questions, target length, structured data). An agent can identify this tool without opening the schema.

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?

Gives concrete workflow guidance: where to source competitor URLs (own search tool, Ahrefs, Semrush, or the user, 1-3) and the conditional use of url (improving an existing page). It cross-references start_site_audit for audit_id. It lacks explicit when-not-to-use guidance versus brief-adjacent siblings, so it falls short of a 5.

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