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

readOnlyHint=true already tells the agent this is a safe read, and the description's only extra is the raw endpoint (POST /v1/reports/data:fetch), which is marginal. It says nothing about pagination behavior, whether period is mandatory, or how large a result set can be.

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 tight sentences with the purpose front-loaded and no filler. The API endpoint sentence is low value for an agent but does not bloat the definition.

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 8 parameters, no output schema, and vague phrasing like 'table data', the agent has no idea what the returned rows/columns look like or how grouping affects output. It is callable from the schema but the return contract is undefined.

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 88%, so the schema already carries parameter meaning (report_id provenance, obfuscated ids, RFC 3339 dates, page_token semantics). The description adds nothing beyond that, which is the baseline case.

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: fetching the table data of one report for a time period. This clearly separates it from moego_list_reports (which enumerates reports) without naming that sibling 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?

The phrase 'for a time period' implies period_start/period_end should be supplied, but there is no explicit when-to-use guidance and no mention of when not to use it or what alternative to pick. Usage must be inferred from the params and the sibling list.

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