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

Annotations already declare non-readOnly, idempotent, non-destructive behavior, so the safety profile is covered. The description adds useful behavioral detail (arbitrary field patches plus a focus/zoom crop mode that alters what the tile displays), but says nothing about permissions or what happens to fields not included in the patch.

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 core operation, then the crop special case; every clause earns its place. Slightly terse JSON-in-prose formatting, but no wasted sentences.

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 2-param mutation tool with no output schema and a vague patch schema, the description covers the main patch surface and the crop mode, but leaves open whether the patch merges with or replaces existing tile fields and what the returned tile looks like.

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% and the patch object is untyped additionalProperties, so the description carries the load. It does this well by enumerating patch keys (size, title, color, text) and fully specifying the crop object including the 0–100 focus range and 1–3 zoom range; only the 'id' parameter is undocumented (reasonably obvious).

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+resource ('Change fields of a tile') and immediately demonstrates the shape of the change with concrete examples. It is distinguishable from siblings like move_tile or add_tile by implication, but sibling differentiation is not made explicit.

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?

Usage is implied rather than stated: the examples show what can be patched, but there is no guidance on when to use this versus move_tile (also a field change) or add_tile, and no prerequisites are mentioned.

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