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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuine behavioral value by disclosing what is reported (image class, ZB number, CRC check results) and the accepted image shapes, but says nothing about failure modes, permissions, or limits.

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?

A single dense sentence front-loads the platform context well, but the closing fragment 'Needs no definition' is opaque and does not earn its place, weakening an otherwise compact layout.

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?

With no output schema, the description usefully previews the return content (image class, ZB number, CRC validity). Given the nested image_file object and closed-world read-only nature, an agent has enough to call it correctly, though selection guidance against siblings remains 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 description coverage is 100%, and image_file's own description plus use_sample's description already document both parameters. The description's mention of the 24 KiB calibration window and 512 KiB flash echoes the schema's nesting description rather than extending it, so the baseline 3 applies.

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 names a specific verb ('say what an image is') and a concrete resource (BMW E46 M3 SMG II / Siemens SMG2 510 ECU image), and enumerates the outputs: image class (24 KiB calibration window vs 512 KiB flash), ZB number, and CRC integrity. It is clearly distinguishable from read/compare siblings, though it never names them explicitly.

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?

There is no statement of when to use this versus smg2_read, smg2_compare, or read_bin. The trailing 'Needs no definition' is cryptic and does not function as usage guidance. An agent must infer the selection criteria from the name alone.

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