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

Annotations already provide readOnlyHint=false, destructiveHint=false, and idempotentHint=true. The description goes beyond these by clarifying the specific behavioral nuance that the change is cosmetic and does not affect slugs/links, and explains the edge case about landing page titles depending on the document's <title>. However, it doesn't mention response format or error conditions, but given the annotations, the added value is substantial and no contradictions exist.

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?

The description is front-loaded with the core purpose and key scoping constraints ('Cosmetic only'), followed by alternative routing. While the landing-page edge case adds some length, it's directly relevant to avoiding incorrect assumptions. The structure is clear and mostly efficient, though the final sentence about return value is somewhat redundant with the schema's implied return.

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?

The description covers the scope, effects, alternatives, and the tricky workspace_id prerequisite. Since the tool is a write operation but non-destructive, and the output schema is absent, the description could mention the exact structure of the returned 'updated site,' but that's a minor gap. Overall, the definition is comprehensive for the tool's complexity.

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 parameters are well-documented in the schema. The description adds value by explaining the workspace_id parameter's nuanced behavior (required on write when multiple workspaces are reachable) and the semantics of the title parameter ('display title' vs. a slug or path). This goes beyond the schema's minimal descriptions, making the tool easier to use correctly.

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 clearly states the verb and resource: 'Rename a site's display title by id.' It also explicitly differentiates from siblings by stating what this tool does NOT change (slug, permalink, existing links) and naming the alternative tools (set_site_slug, update_site) for those actions. This makes the purpose unambiguous and distinct from the 40+ sibling tools.

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 provides explicit when-to-use guidance: it explains that this tool is for cosmetic title changes only, and explicitly states when to use alternatives ('To change the site's link path, use set_site_slug' and 'change that with update_site'). It also clarifies the scope of the effect (what changes, what doesn't), which is critical for correct usage.

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