Change a widget

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

Goes well beyond the annotations: discloses that the merged instance passes the widget's own update() sanitisation and widget_update_callback filter, that HTML is filtered unless the account may post unfiltered HTML, and that credential values omitted by wp_get_widgets stay as stored (including nested) and are omitted from the response. It also states that no undo point is recorded, which matters directly against destructiveHint=true and the wp_undo sibling.

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-loads the action and merge semantics, then layers sanitisation, credential, return and failure details in a single dense paragraph with no filler sentences. The credential clause is somewhat tangled and could be split for readability, but nothing is redundant with the schema or annotations.

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?

With no output schema, the description still names the return payload (updated, id, stored settings), enumerates the three refusal conditions and confirms nothing is saved on failure, and flags the absence of an undo point. An agent has everything needed to call it and interpret the result.

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 earns extra credit by explaining that settings is a shallow merge where a nested value replaces the stored one, and by documenting the credential-omission edge case for settings fields. The id format itself is left to the schema, which already documents it well.

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?

Opens with a specific verb+resource: 'Update the settings of an existing widget instance,' and immediately adds the distinguishing merge semantics (top-level merge, nested replace). It is clearly separable from wp_add_widget and wp_delete_widget by scope, though no sibling is named explicitly.

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?

Implies when to use it ('an existing widget instance') and that wp_get_widgets supplies the id, but never states when not to use it or points at alternatives for creating/removing instances. The failure conditions are described, which helps an agent avoid wasted calls, but routing guidance is only implied.

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