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

Adds genuine behavior beyond the annotations: the provider's native name is kept separately and rewritten on every sync, so the rename survives 'Sync now', and an empty string reverts to it. It also scopes the mutation ('does NOT touch the source'), which usefully clarifies why destructiveHint=true is limited to the local title. It stops short of stating what happens if the activity id is unknown or if an existing custom title is overwritten.

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-loads the action, then the empty-string behavior, then the sync semantics, then the usage trigger. Dense and largely waste-free, though the trailing 'a session you merely read as something else keeps its name' is a second pass at the same exclusion already implied earlier.

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 two-parameter mutation with annotations covering safety and no output schema, the description supplies the non-obvious context an agent needs (sync survival, provider-name preservation, clearing semantics, usage trigger). The only real gap is that the 'id' parameter's expected value/reference is left entirely to inference.

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 0%, so the description must carry both parameters. It handles 'title' well (empty string clears, examples given, and the schema supplies maxLength), but 'id' is never explained beyond being required, leaving half the surface undocumented.

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+resource (give one completed activity the athlete's own title) with a concrete example, and implicitly distinguishes itself from sibling mutators like set_activity_notes, edit_activity and tag_activity by confining the action to the title field. An agent can tell what it does without opening the schema.

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?

Explicitly names the trigger conditions ('when the athlete asks for a rename, or tells you what a generically named session actually was') and an exclusion ('a session you merely read as something else keeps its name'). This is exactly the when/when-not routing an agent needs versus get_activity or edit_activity.

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