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

The description claims a destructive operation ('Delete') while annotations declare readOnlyHint=true, which is a direct contradiction. Additionally, idempotentHint=true conflicts with the described re-indexing behavior, making repeated deletes non-idempotent. This is a serious transparency failure.

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?

The description is a single sentence that efficiently packs the action, indexing rule, scope, re-indexing behavior, and error return. It is front-loaded with the verb and remains concise without unnecessary fluff.

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 simple delete tool with no output schema, the description covers the essential behavioral aspects: what is deleted, scope restriction, re-indexing, and error condition. However, the contradictory annotations introduce confusion that slightly reduces completeness in terms of safe usage expectations.

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 the schema for both parameters (index and session_id) is self-explanatory. The description repeats the index semantics already present in the schema and adds the invalid_index return, but this is marginal beyond schema coverage. 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?

The description clearly states 'Delete a specific entry from your captain's log' with precise indexing semantics (0 newest, higher older). This distinguishes it from sibling tools like captains_log_add, get, and list, specifying the action and resource unambiguously.

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?

The description provides clear context on when to use this tool: to delete one of your own log entries, with specifics about index behavior and re-indexing. It does not explicitly list alternatives or exclusion criteria, but the usage context is well implied by the scope constraint 'Only your own log entries can be deleted'.

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