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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the safety profile is covered. The description adds genuinely new context: it is FREE (no credits) and that it is a MUTATION, plus append-only single-entry semantics ('add one ... entry'). It does not describe anything contradictory.

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?

One tight sentence with the resource and verb front-loaded and examples inline. The 'Link Building Tool:' prefix is slightly redundant but provides category context cheaply.

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 3-required-param mutation with no output schema, the description covers purpose, cost, and mutating nature, while annotations carry the safety/idempotency profile and the schema documents two of three params. Only minor gap is the return/confirmation behavior, which is arguably not essential.

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 67% and both projectId and prospectId carry their own 'get one from list_projects / list_link_prospects' descriptions. The description adds content examples that clarify the note parameter's intent, but nothing about length limits or format beyond the schema. Baseline 3 is appropriate.

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+resource: 'add one manual activity-log entry to a prospect', with two concrete examples ('emailed on 9/5', 'follow-up sent') that pin down what a 'note' is. It is distinguishable from list_link_prospect_activity (read) and add_link_prospect (create prospect), though it doesn't 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?

Usage is implied by the examples and by 'one manual activity-log entry', giving an agent a reasonable sense of when to log an activity. However there is no explicit when-not guidance and no routing to related siblings like update_link_prospect_status for actual status changes.

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