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

Goes beyond the annotations by naming downstream effects: reads feed get_poetry_reading_stats rankings and daily reading connections. 'Each call adds one more read' reinforces the non-idempotent behavior declared in annotations with a concrete consequence. It stops short of describing failure modes (e.g., unknown identifier) for a mutation, so not a 5.

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-loaded with the core action, then usage trigger, then behavioral consequence, then compact examples. Every sentence carries information and nothing is redundant.

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 2-parameter mutation with full annotations and an output schema, the definition covers what it does, when to invoke it, side effects, and the section handling rule. Nothing an agent needs to call 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 3 is the baseline; the description earns above that by giving worked examples of both the identifier-only and identifier+section call shapes, clarifying the 'poet/poem' anchor format by reference to get_poem.

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?

Specific verb and resource: 'Records that the reader read a poem from the ReadingRate collection, adding one read to its count.' This clearly separates it from log_reading_session (session-level) and save_poem_line (saving a line rather than a read event).

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?

Explicit trigger conditions: 'Use when the reader says they read or reread a poem, or asks to mark one as read,' plus the constraint that multi-section works are logged one section at a time. It does not explicitly name an alternative sibling (e.g., log_reading_session) for contrast, so a 4 rather than 5.

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