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

Annotations already cover the write/side-effect profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false, openWorldHint=false), so the bar is lower. The description adds genuinely non-structured context: no external SEO provider is called, no credits are spent, and a hard cap of 100 notes per config – all useful operational facts not present in annotations.

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?

Three tight sentences with zero filler, front-loaded with the core action followed by cost, scope, and limit. Every clause carries information the agent can act on.

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 4-param write with a fully-described schema and no output schema, the description covers cost, scope, and the 100-note constraint. It lacks only a pointer to the read/remove counterparts, so it is complete enough but not exhaustive.

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 schema already documents projectId, configId, date, and label, including the config-lookup hint via get_rank_tracker. The description reinforces that configId is config-level rather than keyword/device scoped, a marginal add over the schema, landing at the baseline.

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 – 'Adds a chart note to a rank tracker's own timeline' – which is precise and distinguishable from sibling writes like add_rank_tracking_keywords or add_link_prospect_note. The object (a chart annotation on the rank timeline) is unambiguous.

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?

Clarifies when this applies with 'Config-level, not per-keyword or per-device,' which tells the agent the correct scope before calling. It does not name the natural alternatives (list_rank_annotations / remove_rank_annotation) or exclusions, so it stops short of a 5.

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