Get person thumbnail

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so 'Read-only' merely restates them. The description does add useful behavior detail: the payload is a face crop delivered as base64 with a MIME type, which tells the agent what it is actually receiving. It says nothing about size limits, fallbacks when no face is detected, or error behavior.

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 purpose followed by usage, then Args and Returns sections; every line is scannable. The 'Read-only' sentence duplicates an annotation and is the one piece of low-value text.

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 single-parameter read tool, the description covers intent, usage trigger, parameter meaning, and return shape. The Returns paragraph is somewhat redundant given an output schema exists, but no essential calling information is missing.

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% with a bare 'Person Id' string property, so the description carries the burden and does so by specifying the value is the person's UUID. That is concrete added meaning beyond the schema, though format examples or sourcing (e.g. from list_people) are absent.

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?

Names a specific verb and resource ('Get a base64-encoded face crop thumbnail for a person'), which clearly separates it from asset-level siblings like get_asset_thumbnail. It does not explicitly name a sibling to avoid, 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?

'Use this to visually identify a person before merging or renaming' gives a concrete intent that maps onto the merge_people/update_person siblings. There is no explicit when-not guidance or statement of prerequisites, so it is clear but not exhaustive.

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