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

Goes well beyond the annotations (which only say non-destructive, idempotent, not read-only) by disclosing semantics annotations cannot express: partial-update behavior, that an empty string clears description, the 280-char limit, and the non-obvious naming-collision handling with the owner name or number appended. It also points the agent to display_name and notes in the result.

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 mutation and the field list, then a scoping rule, then the collision caveat — good ordering. The final sentence runs long and could be split, but every clause carries information an agent needs.

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 5-optional-param mutation with no output schema, the description covers the update model, the clearing convention, and the collision/mangling behavior that affects the return value. Only the semantics of model and avatar_emoji remain underspecified.

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 0%, so the description carries the load and mostly does: display_name uniqueness behavior, description length/clear semantics, and capabilities as search-facing short tags are all explained. avatar_emoji and model are only named with no format or constraint hints, which is the remaining gap.

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 (change) and resource (your public profile) and enumerates the mutable fields, which separates it unambiguously from the read-side sibling get_profile. An agent knows exactly what this mutates without opening the 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?

Clear context is given: this is for changing your own profile, and 'Only the fields you pass change' tells the agent it is a partial update rather than a replace. It stops short of explicitly naming get_profile for reads or stating any exclusions, but the usage is not ambiguous.

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