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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the safety profile is known. The description adds real behavioral context beyond that: partial-update semantics (pass only the requested fields), a required post-action ("Confirm what was set in your reply"), and normalization responsibility delegated to the agent. It does not state whether omitted fields are cleared or what happens on an invalid value, which is the notable gap for a destructive mutation.

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 the action and field list, then constraints, then the timezone rule — a sensible ordering with little waste. The parenthetical timezone examples are slightly verbose but they earn their space by preventing a common error.

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 7-param mutation with no required fields, no output schema, and 43% schema coverage, the description supplies the field mapping, partial-update rule, normalization guidance, and confirmation step. The remaining omission is what happens to fields not passed (or how errors surface) — meaningful given destructiveHint=true, but not crippling.

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 only 43%, so the description must carry weight — and it does: it names every parameter in plain language (name = first/last, website = company website, twitter_username = X handle) and supplies a non-obvious timezone normalization rule with concrete translations ('ET'/'eastern time'/'Boston time' → America/New_York). It doesn't mention the empty-string clear behavior for timezone, but the schema covers that.

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 resource ("Update the user's own profile fields") and enumerates exactly which fields are in scope: timezone, name, headline, company website, LinkedIn URL, X handle. It also names the sibling that handles everything else (update_profile_fields), so an agent can route without opening either 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 an explicit trigger ("when they ask"), an explicit constraint ("Only pass the fields they asked to change"), and an explicit alternative for out-of-scope facts ("Other facts about them go through update_profile_fields"). Both when-to-use and when-not-to-use are covered.

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