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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds genuinely new behavioral context beyond them: no external SEO data provider is called, no credits are spent, results are ordered oldest-first, and scope is config-level rather than per-keyword or per-device.

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, front-loaded with the core concept, then the cost profile, then the scope. Each sentence carries distinct information with no filler, though the opening 'Chart notes' phrasing is slightly idiomatic.

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-param read tool with no output schema, the description conveys what is returned (dated chart notes on a timeline), the ordering, and the scope. It is close to complete, though it does not describe the per-annotation fields (date, text, author) an agent might need when consuming the result.

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 100% and both required params (projectId, configId) are documented in the schema with sourcing hints. The description reinforces that configId is the scoping unit via 'config-level, not per-keyword or per-device', but adds no syntax or format detail beyond the schema, so the baseline of 3 applies.

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?

The description states a specific resource ('Chart notes on a rank tracker's own timeline') with concrete examples ('deployed new title tags', 'algorithm update') and an ordering rule ('oldest first'). It distinguishes itself from per-keyword/per-device siblings by declaring config-level scope, though it never names the add_rank_annotation/remove_rank_annotation siblings by name.

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?

Usage context is implied rather than stated: the FREE/no-credits note tells an agent this call is cheap and safe to make freely, and the config-level framing hints when it applies. But there is no explicit 'use this before/after X' or a named alternative, so an agent must infer when to reach for it.

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