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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, and the description adds real value on top: 'Each call adds a new note' spells out the append/non-idempotent behavior in plain terms, and 'The line is not saved as a quote' clarifies the side-effect boundary. It stops short of describing failure modes or what happens on a bad anchor, 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 purpose sentence, then usage, then the alternative, then a compact example. Every sentence carries a distinct fact (destination, exclusion, append semantics, format) with no repetition.

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 write tool with an output schema and full annotation coverage, this covers what an agent needs: where the note goes, that it is not a quote save, that calls accumulate, and a concrete anchor example. Return values are handled by the output schema, so no further detail is required.

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 worked example {"anchor": "wyatt/whoso-list-to-hunt/13", "note": "..."} goes beyond the schema by demonstrating the concrete anchor format, which the schema only describes abstractly as 'as get_poem or search_poems returns it'. The note parameter itself gets no extra semantic guidance.

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 (writes) and resource (the reader's note on one line of a poem) plus the destination (ReadingRate notes). It also names the adjacent concept it is not — 'The line is not saved as a quote' — and points at save_poem_line, so an agent can distinguish it from siblings without opening schemas.

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 an explicit trigger ('Use when the reader wants to record a thought about a specific line of a poem') and an explicit alternative with its selecting condition ('To save the line itself as a quote, use save_poem_line'). Nothing is left to inference.

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