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

Annotations already signal the operation is a write (readOnlyHint=false) and non-destructive (destructiveHint=false). The description adds value beyond annotations by explaining the consequence of not updating the character and emphasizing account ownership, which helps agents understand scope and authorization. No contradiction with annotations.

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?

Two sentences deliver the core action, the consequence of neglect, and a critical prerequisite with no filler. The most important information is front-loaded and every clause 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 simple update tool with annotations present and no output schema, the description covers purpose, ownership prerequisite, and why the tool matters. It omits an explicit return-value note, but that is a minor gap given the simplicity of the operation.

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 0%, so the description must compensate. It explicitly names display_name and personality_notes and clarifies the account requirement, but it does not explain entity_id or how the parameters interact beyond 'and/or'. This is partial but adequate compensation.

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 states a specific action ('Save a character's display name and/or personality notes') with a clear resource, making it obvious this is an update operation on a character. It does not explicitly name sibling tools like create_character for differentiation, so it stops short of a 5.

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 gives useful context about when this is needed ('Without this, a character stays 'Untitled Character'...') and specifies a prerequisite ('account must be whichever farm account's project owns this entity_id'). It does not explicitly compare against create_character or other siblings, so it earns a 4 rather than a 5.

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