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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: the meaning and units of each record_type, the shape of value, and the fallback that an unknown slug returns `candidates` rather than an error. No mention of pagination or result-size limits.

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?

Four dense sentences, front-loaded with the usage trigger and then the data model. The parenthetical examples and unit annotations all earn their place; there is no filler or repetition of schema content.

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?

With an output schema present, return values needn't be spelled out, yet the description still documents record fields and the unknown-slug candidate behavior. For a two-param, no-required-param read tool it is close to complete; only ordering/pagination behavior is unaddressed.

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 0%, so the description must carry the burden, and it largely does: it defines each record_type value with units ('max_weight' kg, 'max_volume' weight×reps, 'estimated_1rm' kg) and explains the AND/omit semantics of exercise_slug and kind. It never describes the expected format of exercise_slug itself, leaving that parameter partly opaque.

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 (retrieve personal records) and grounds it with concrete user phrasings ('what are my PRs?', 'what is my heaviest squat?'), which cleanly separates it from neighbors like get_exercise_progression or get_stats_overview. An agent can match an intent to this tool 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?

Provides an explicit activation trigger ('Use this when the user asks about their personal records') and explains the filtering decision: filter by exercise_slug and/or kind, or omit both for all. It does not state when to prefer a sibling tool (e.g. progression or stats) instead, so it falls short of the 5 bar.

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