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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description goes further by disclosing the exact failure mode ('REFUSED with tableau = PAS_OUVERT' when the contract is not deployed) and the backing endpoint. That error contract is the kind of detail annotations cannot carry. It stops at 4 because there is no mention of caching/refresh semantics for a board that changes server-side.

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?

Two sentences, front-loaded with the action and endpoint, with the field list packed into a parenthetical rather than padded into prose. The refusal clause is placed after the payload description, which is reasonable. Slightly dense, but nothing is wasted.

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 no output schema, the description carries the return-shape burden and does so by naming the contract plus each mission field. It also covers the error condition and confirms the absence of inputs. For a zero-parameter read tool, an agent has everything needed to call it and interpret 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?

The tool takes zero parameters, so the baseline is 4. The description reinforces this with 'no input', which matches the empty schema and additionalProperties: false, leaving no ambiguity for the caller.

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?

Names a specific verb and resource ('Reads the Block Missions board') and even pins the underlying endpoint (GET /api/missions), plus enumerates the payload shape (id, reward token/amount, done/maxDone, holding, state). That is far more specific than a tautology. It does not explicitly contrast itself with siblings like tblock_pairs or tblock_game_state, so it stops short of a 5.

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 only implied: an agent infers it should call this when it needs mission-board state. There is no statement of when to prefer it over tblock_game_state or tblock_pairs, and no workflow context. The one genuinely useful signal is the precondition that the call is REFUSED while the contract is undeployed, which is a partial substitute for real guidance.

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