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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the write profile is covered structurally. The description adds that exactly one line is written and that an id is returned, which is useful, but with an output schema present the return-value note is redundant and it says nothing about auth needs or duplicate-line behavior implied by non-idempotence.

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 tight sentence with the action front-loaded and no filler. Every clause carries information, though the return-value clause is arguably redundant given the output schema.

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?

The existence of an output schema excuses omitting return details, but with 0% schema coverage on parameters the description leaves the agent without any guidance on what to supply for `event` or `detail`. Combined with absent usage guidance, this is incomplete for a two-parameter write tool.

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%, so the description must carry the burden for two parameters, yet it never names or explains `event` or `detail`. 'One audit line' gestures at the payload but does not differentiate the required event from the optional detail or indicate accepted formats.

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 and resource: 'Write one audit line for a step of the chain.' This is clearly a mutation that appends an audit record, and no sibling tool competes for that role. It stops short of 5 only because 'step of the chain' is domain jargon left undefined.

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 phrase 'for a step of the chain' hints at context but gives no explicit when-to-use guidance, no prerequisites, and no alternatives among the 19 sibling tools. Nothing tells the agent when this call is appropriate versus other logging or handoff tools.

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