updateUserPhoto

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

The description adds value beyond annotations by stating 'Fields omitted are untouched' (aligning with idempotentHint) and 'Writes live data'. It also describes the return format. No contradictions 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?

The description is highly structured with clear sections, front-loaded main sentence, and no unnecessary words. Every sentence serves a purpose (use case, required param, enums, see also, returns).

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?

Given the tool has 3 parameters and no output schema, the description covers purpose, usage, return format, and sibling distinctions. It lacks detailed explanation of _clear_fields but the schema covers that. Overall complete for the complexity.

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?

The description repeats enum values already in schema and mentions the required photo_id, but does not explain the meaning of photo_id or type beyond the enum. Schema description coverage is 33%, and the description partially compensates by restating enums, but misses adding new semantic context.

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 clearly states the tool updates an existing user photo record by ID. It distinguishes from sibling tools by explicitly referring to createUserPhoto and deleteUserPhoto, clarifying its role as an update operation.

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 'Use when' section provides a clear, specific scenario: changing a photo's type slot. It also references create and delete alternatives, but does not explicitly exclude other use cases or compare with other update tools like updateUser.

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