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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds one useful behavior (no binary upload) but omits what 'eligible' means, what happens to the previous failed attempt, and whether the retry is rate-limited or asynchronous.

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?

Two short sentences with the action and its precondition front-loaded; nothing is padded. The second sentence is slightly cryptic in phrasing ('MCP does not upload binaries') but still earns its place as a scope boundary.

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?

An output schema exists, so return values need not be explained. Still, for a state-mutating retry tool with zero annotation-level detail about eligibility or failure modes, the description leaves the agent guessing about preconditions and outcomes.

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 0% and the description never mentions the required 'id' parameter, so it contributes no semantics beyond the schema. For a mutation that acts on one specific stored file, it should clarify whether 'id' is the ECU file id versus a session or vehicle id.

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 ('Retry') and resource ('ECU file') and narrows the target with two qualifiers: 'eligible' and 'failed, already stored'. That is enough to separate it from process_ecu_file and inspect_ecu_file, though it never names those siblings 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?

'Eligible failed, already stored' implies the precondition for use, and 'MCP does not upload binaries' draws a boundary. However, it never says what to use instead to upload or to first process a file, so the agent must infer the routing from sibling names alone.

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