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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered. The description adds genuinely new behavioral context beyond them: it is free, requires no sign-in, and its output is 'generic' versus signed-in tools that use the user's own data. This is useful for setting expectations, though it could say more about what the output looks like.

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 tight sentences with zero redundancy, and the trigger condition is front-loaded before the alternatives and exclusion. Every sentence earns its place.

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 3-parameter generation tool with no output schema, the description covers trigger, exclusion, alternative routing and the nature of the output. Parameter-level detail is fully handled by the schema (including maxLength and enum). Only a richer sense of what the returned bio looks like is missing, which is minor since no output schema exists.

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 100%, so platform, current_bio and niche are already documented in the schema. The description repeats the platform list but adds no format, length or syntax guidance beyond what the schema provides, so the baseline 3 applies.

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 (rewrite) and resource (profile bio) and enumerates the exact platforms covered (Instagram, YouTube, TikTok, X, LinkedIn). It also positions itself against the signed-in writing tools, so an agent can distinguish it from xcut_write_caption or xcut_write_content.

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?

Provides an explicit trigger ('when the user wants their profile bio rewritten'), an explicit exclusion ('Do not use for writing unrelated to social media or marketing content'), and routes to the correct alternative ('for work based on the user's own posts, canvases or brand, use the signed-in XcutAI tools'). All three when/when-not/alternative elements are present.

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