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

Annotations already declare readOnly/idempotent/non-destructive, yet the description adds substantial context beyond them: every widget is a local Postgres read with no upstream call, no paid-provider credit or live Search Console quota is consumed, and it documents tracker-scope semantics (rank_volatility/share_of_voice read only the first active tracker; rank_movers sums across all). This is exactly the kind of non-obvious behavior an agent needs.

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 purpose, then layers cost and tracker-scope constraints in dense, non-redundant sentences. Nothing is padding — every clause conveys a distinct behavioral fact.

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 read-only render tool with full schema coverage and complete annotations, the description covers safety, cost, and rendering scope well. It does not describe the return shape, but with no output schema and readOnly annotations that omission is minor.

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% and every parameter (projectId, periodDays, reportDefinitionId) is fully documented in the schema, so baseline 3 applies. The description adds no parameter-level syntax or format detail; its widget notes concern report content, not the inputs.

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 ('Renders a report definition') and immediately clarifies scope: it fetches only the definition's selected widgets rather than a fixed set. This distinguishes it in spirit from get_report_definition (config retrieval) and list_report_definitions, though it does not name 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?

The FREE/cost note implicitly signals 'safe to call freely,' but there is no explicit when-to-use guidance or comparison against the obvious alternatives (get_report_definition for config, list_report_definitions for IDs). Usage must be inferred.

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