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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so the safety profile is covered. The description adds useful context beyond that: the return payload ('full text content + metadata for the AI to cite') and a concrete failure warning (expense ids are never sheet row numbers because rows shift), which is genuinely non-obvious behavioral information.

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-loads the core action, then bullets the three id families with examples. The encoded example strings ('expense:RR-123%3A%3Adrive%2Ffile%209') are somewhat dense, but each sentence carries actionable content rather than filler.

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 with an output schema, this is complete: it covers every accepted id form, how to obtain each, the exact-usage constraint, and what comes back. Nothing an agent needs to invoke it correctly 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 100%, so the baseline is 3. The description exceeds that by expanding the id grammar with real examples, the URL-encoding requirement, and the row-number pitfall — meaning the agent understands more than the regex pattern alone conveys.

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 (fetch full details for a specific item) and constrains it to items previously returned by `search`. It distinguishes itself from the list-oriented `search` sibling, but does not differentiate from detail-oriented siblings like `get_expense_by_id` or `get_report_details`, so an agent may not know which detail tool to pick.

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?

Gives clear context: use it on an id returned by `search` or `list_reports`, and 'always use the id exactly as returned... do not invent or modify.' It names the producing tools but offers no when-not-to-use guidance or routing against the other detail tools.

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